Important Questions For You!

Chemistry is an important subject in ICSE Class 10, as the fundamentals studied now will also be helpful in the competitive exams like IIT-JEE and NEET. TopperLearning presents study materials for ICSE Class 10 Chemistry to help students to score well in the examination. All our study materials are created by subject experts and give basic insight on about how and what to prepare for the final exams.

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Chapter 1: Periodic Table, Periodic Properties and Variations of Properties

1. Define the following terms:                                                                                                                                  [3M]

  1. Ionisation potential
  2. Electronaffinity
  3. Electronegativity

2. In Period 3 of the periodic table, Element B is placed to the left of Element A. On the basis of this information, choose the correct word from the brackets to complete the following statements:                                                                                     [3M]

  1. Element B would have (lower/higher) metallic character than Element A.
  2. Element A would probably have (lesser/higher) electron affinity than Element B.
  3. Element A would have (greater/smaller) atomic size than Element B.

3. An element has an atomic number 16.State                                                                                                            [3M]

  1. the period to which it belongs
  2. the number of valence electrons
  3. whether it is a metal or non-metal

4. Give reasons:                                                                                                                                                      [3M]

  1. The oxidising power of elements increases on moving from left to right along a period in the periodic table.
  2. Ionisation potential of the element increases across a period.
  3. Alkali metals are good reducing agents.

5. Use the letters only written in the periodic table given below to answer the questions that follow:                              [4M]

  1. State the number of valence electrons in atom J.
  2. Which element as shown forms ions with a single negative charge?
  3. Which metal element is more reactive than R?
  4. Which element has its electrons arranged in four shells?

6. Arrange the following as per the instructions given in the brackets:                                                                          [4M]

  1. Cs, Na, Li, K, Rb (increasing order of metallic character)
  2. Mg, Cl, Na, S, Si (decreasing order of atomic size)
  3. Na, K, Cl, S, Si (increasing order ionisation energy)
  4. Cl, F, Br, I (increasing order of electron affinity)

7. A group of elements in the periodic table is given below: (Boron is the first member of the group and thallium is the last.)
Boron, Aluminium, Gallium, Indium, Thallium Answer the following questions in relation to the above group of elements:   [5M]

  1. Which element has the most metallic character?
  2. Which element would be expected to have the highest electronegativity?
  3. If the electronic configuration of aluminium is 2, 8, 3, how many electrons will there be in the outermost shell of thallium?
  4. The atomic number of boron is 5. Write the chemical formula of the compound formed when boron reacts with chlorine.
  5. Will the elements in the group to the right of this boron group be more metallic or less metallic in character? Justify your answer.

8. An element has 2 electrons in its N shell.                                                                                                                 [4M]

  1. What is its atomic number?
  2. State its position in the periodic table.
  3. Is it a metal or non-metal?
  4. State the name assigned to this group.

Chapter 2: Chemical Bonding

1. What is the difference between                                                                                                                               [3M]

  1. Ionic compounds and polar covalent compounds
  2. Ionic compounds and covalent compounds
  3. Polar covalent compounds and non-polar covalent compounds

2.                                                                                                                                                                            [3M]

  1. What are redox reactions?
  2. Why is the reaction between manganese dioxide and hydrochloric acid a redox reaction?
  3. Identify the substance oxidised and the substance reduced in the above reaction.

3.                                                                                                                                                                           [3M]

  1. State the type of bonding in the following molecules:
    a) Ammonia
    b) Calcium oxide
  2. Draw an electron dot diagram to show the formation of each of the following compounds:
  1. Methane
  2. Magnesium chloride
    [H = 1, C = 6, Mg = 12, Cl = 17]

4. Draw the orbit structure and electron dot diagrams of                                                                                            [3M]
(i) NaCl (ii) MgCl2 (iii) CaO

5. A compound has the formula H2Y (Y= non-metal). State the following:                                                                    [4M]

  1. Outer electronic configuration of Y
  2. Valency of Y
  3. Bonding present in H2Y
  4. Formula of the compound formed between calcium[20Ca 40 ] and Y

6. Predict the type of bonding in the following molecules:                                                                                            [5M]

  1. Oxygen
  2. Calcium oxide
  3. Water
  4. Methane
  5. Ammonium ion


Chapter 3: Acids, Bases and Salts

1. Give balanced chemical equations for the following:                                                                                                 [3M]

  1. Magnesium with Hydrochloric Acid
  2. Sulphuric acid with Sodium hydroxide
  3. Sodium with Sulphuric acid

2. Why don you use universal indicator, you see that solutions of different acids produce different colours. Indeed, solution of the same acid with different concentrations will also give different colours. Why?                                                                 [3M]

3. Define the following as per ionic theory with examples and ionic equations wherever relevant.                                     [3M]

  1. Acid
  2. Base
  3. Alkali

4.                                                                                                                                                                             [3M]

  1. What is the pH of pure water?
  2. What is the purpose of the pH scale?
  3. A is a soluble acidic oxide and B is a soluble base. On comparing to the pH of water, what will be the pH of solution A and solution B?

5. You have been provided with three test tubes. One of them contains distilled water and the other two have an acidic solution and a basic solution respectively. If you are given red litmus paper, how will you identify the contents of each test tube?         [4M]

6. Give one example in each case:                                                                                                                              [5M]

  1. A basic oxide which is soluble in water.
  2. A hydroxide which is highly soluble in water.
  3. A basic oxide which is insoluble in water.
  4. A hydroxide which is insoluble in water.
  5. A weak mineral acid.
  6. A base which is not an alkali.
  7. An oxide which is a base.
  8. A hydrogen-containing compound which is not an acid.

7. Give one example in case-                                                                                                                                     [5M]

  1. A basic oxide which is soluble in water.
  2. A hydroxide which is highly soluble in water.
  3. A basic oxide which is insoluble in water.
  4. A hydroxide which is insoluble in water.
  5. A weak mineral acid.
  6. A base which is not alkali.
  7. An oxide which is a base.
  8. An oxide which is acid.
  9. A hydrogen containing compound which is not an acid.
  10. A base which does not contain a metal ion.

Chapter 4: Analytical Chemistry – Use of Ammonium Hydroxide and Sodium Hydroxide

1. Identify the salts P and Q from the observations below:                                                                                          [2M]

  1. On performing the flame test, salt P produces a lilac-coloured flame and its solution gives a white precipitate with silver nitrate solution, which is soluble in ammonium hydroxide solution.
  2. When dilute HCl is added to salt Q, a brisk effervescence is produced and the gas turns limewater milky.When NH4OH solution is added to the above mixture (after adding dilute HCl), it produces a white precipitate which is soluble in excess NH4OH solution.

2. State your observations when ammonium hydroxide solution is added drop by drop and in excess to each of the following solutions:                                                                                                                                                                [2M]

  1. Copper sulphate solution
  2. Zinc sulphate solution

3. Identify the cations in each of the following cases:                                                                                                 [3M]

  1. NaOH solution when added to Solution (A) gives a reddish brown precipitate.
  2. NH4OH solution when added to Solution (B) gives a white precipitate which does not dissolve in excess.
  3. NaOH solution when added to Solution (C) gives a white precipitate which is insoluble in excess.

4. Give a chemical test to distinguish between the following pairs of chemicals:                                                             [4M]

  1. Lead nitrate solution and zinc nitrate solution
  2. Sodium chloride solution and sodium nitrate solution
  3. Ammonium hydroxide and sodium hydroxide
  4. Dilute sulphuric acid and dilute hydrochloric acid

5. The following table shows the test a student performed on four aqueous solutions X, Y, Z and W. Based on the observations provided, identify the  cation present:                                                                                                                         [4M]

Chapter 5: Mole Concept and Stoichiometry

1. Calculate the number of gram atoms in 4.6 grams of sodium (Na = 23)                                                                  [2M]

2. A gaseous hydrocarbon contains 82.76% of carbon. Given that its vapour density is 29, find its molecular formula. [C = 12, H = 11]                                                                                                                                                                       [2M]

3. Calculate the percentage of water of crystallization in CuSO4.5H2O
(H = 1, O = 16, S = 32, Cu = 64)                                                                                                                            [2M]

4. A compound of X and Y has the empirical formula XY2. Its vapour density is equal to its empirical formula weight. Determine its molecular formula.                                                                                                                                                  [3M]

5. A cylinder contains 68 g of ammonia gas at STP.                                                                                                    [3M]

  1. What is the volume occupied by this gas?
  2. How many moles of ammonia are present in the cylinder?
  3. How many molecules of ammonia are present in the cylinder?
    [N = 14, H = 1]

6. The mass of 11.2 litres of a certain gas at STP is 24 g. Find the gram molecular mass of the gas.                               [3M]

7. A gas cylinder can hold 1 kg of hydrogen at room temperature and pressure.                                                            [2M]

  1. Find the number of moles of hydrogen present.
  2. What weight of CO2 can the cylinder hold under similar conditions of temperature and pressure? (Atomic masses: H = 1, C = 12, O = 16)

Chapter 6: Electrolysis

1. Give reasons why.                                                                                                                                               [3M]

  1. Sodium chloride will conduct electricity only in the fused or aqueous solution state.
  2. In the electroplating of an article with silver, the electrolyte sodium argentocyanide solution is preferred over silver nitrate solution.
  3. Although copper is a good conductor of electricity, it is a non-electrolyte.

2. Three electrolytic cells A, B and C are connected in separate circuits. Electrolytic cell A contains sodium chloride solution. When the circuit is completed, a bulb in the circuit glows brightly. Electrolytic cell B contains acetic acid solution, and here, the bulb in the circuit glows dimly. The electrolytic cell C contains sugar solution, and the bulb does not glow. Give reason for each of these observations.                                                                                                                                                            [3M]

3. State the observations at the anode and cathode during the electrolysis of                                                                  [3M]

  1. Fused lead bromide using graphite electrodes
  2. Copper sulphate solution using copper electrodes

4. The following questions are related to the electroplating of an article with silver:                                                           [4M]

  1. Name the electrode formed by the article to be plated.
  2. Which ion must be present in the article to be plated?
  3. Name the electrolyte used for the electroplating of the article with silver.
  4. Give the application of electrolysis.

5. Answer the following questions about the electroplating of copper wire with silver:                                                        [4M]

  1. What ions must be present in the electrolyte?
  2. Of what substance must the anode be made?
  3. What will be made the cathode?
  4. What is the equation for the reaction which takes place at the cathode?

Chapter 7: Metallurgy
1.                                                                                                                                                                               [2M]

  1. Name the most common ore of the metal aluminium from which the metal is extracted. Write the chemical formula of the ore.
  2. (Name the process by which the impure ore of aluminium is purified by using a concentrated solution of an alkali.

2. Answer the following questions                                                                                                                                  [2M]

  1. Give the balanced equation for the reaction between iron oxide (III) and carbon monoxide.
  2. Explain why powdered coke is sprinkled over the electrolytic mixture.

3. For each of the substances listed below, describe the role played in the extraction of aluminium.                                    [3M]

  1. Cryolite
  2. Sodium hydroxide
  3. Graphite 

4.                                                                                                                                                                               [5M]

  1. Give the name and formula of the ore of zinc.
  2. Write equations for the following steps in the extraction of zinc:
    i. Roasting of ore
    ii. Reduction of zinc compound which is the product of the above reaction.
  3. What is add into the blast furnace in addition to zinc compound?
  4. State one large scale use of zinc.
  5. Name the process by which zinc is purified.

5. Name the following:                                                                                                                                                [4M]

  1. Process of coating of iron with zinc.
  2. Alloy of lead and tin which is used in electrical circuits.
  3. Ore of zinc containing its sulphide.
  4. Metal oxide which can be reduced by hydrogen.

6.                                                                                                                                                                               [4M]

  1. Name the solution used to react with bauxite as a first step in obtaining pure aluminium oxide in Bayer’s process.
  2. Write the equation for the reaction where aluminium oxide for the electrolytic extraction of aluminium is obtained by heating aluminium hydroxide.
  3. Name the compound added to pure alumina to lower the fusion temperature during the electrolytic reduction of alumina.
  4. Write the equation for the reaction which occurs at the cathode during the extraction of aluminium by electrolysis.

7. M is a metal above hydrogen in the activity series and its oxide has the formula M2O. This oxide when dissolved in water forms the corresponding hydroxide which is a good conductor of electricity. In the above context, answer the following:                 [5M]

  1. What kind of combination exists between M and O?
  2. How many electrons are there in the outermost shell of M?
  3. Name the group to which M belongs.
  4. State the reaction occurring at the cathode.
  5. Name the product at the anode

Chapter 8: Hydrogen Chloride

1. For the preparation of hydrochloric acid in the laboratory:                                                                                            [2M]

  1. Why is direct absorption of hydrogen chloride gas in water not feasible?
  2. What arrangement is done to dissolve hydrogen chloride gas in water?

2. Identify the gas evolved and give the chemical test in each of the following cases:                                                         [2M]

  1. Dilute hydrochloric acid reacts with sodium sulphite
  2. Dilute hydrochloric acid reacts with iron (II) sulphide

3. The following questions pertain to the laboratory preparation of hydrogen chloride gas:                                                  [3M]

  1. Write the equation for its preparation mentioning the condition required.
  2. Name the drying agent used and justify your choice.
  3. State a safety precaution you would take during the preparation of hydrochloric acid.

4.                                                                                                                                                                                [3M]

  1. What is aqua regia?
  2. State the use of aqua regia.
  3. What is the function of HCl in the preparation of aqua regia?

5. Study the figure given below and answer the questions which follow:                                                                             [3M]

  1. Identify gas Y.
  2. What property of gas Y does this experiment demonstrate?
  3. Name another gas with the same property which can be demonstrated by this experiment.

Chapter 9: Ammonia

1.                                                                                                                                                                                 [2M]

  1. State why concentrated sulphuric acid is not used for drying ammonia gas.
  2. Why is ammonia gas not collected over water?

2. Give balanced chemical equations for each of the following:                                                                                           [3M]

  1. Laboratory preparation of ammonia using an ammonium salt
  2. Reaction of ammonia with excess chlorine
  3. Reaction of ammonia with sulphuric acid

3. Explain the following:                                                                                                                                                 [3M]

  1. Dilute nitric acid is generally considered a typical acid but not so in its reaction with metals.
  2. Concentrated nitric acid appears yellow when it is left standing in a glass bottle.
  3. An all-glass apparatus is used in the laboratory preparation of nitric acid.

4. Give a balanced chemical equation for each of the following:                                                                                         [4M]

  1. Action of conc. nitric acid on sulphur
  2. Catalytic oxidation of ammonia
  3. Laboratory preparation of nitric acid
  4. Reaction of ammonia with nitric acid

5. Give reasons for the following:                                                                                                                                   [4M]

  1. Liquid ammonia is used as a refrigerant in ice plants.
  2. Aqueous solution of ammonia is used for removing grease stains from warm clothes.
  3. Aqueous solution of ammonia gives a pungent smell.
  4. Aqueous solution of ammonia conducts electricity.

Chapter 10: Nitric Acid

1.                                                                                                                                                                                [2M]

  1. What is the type of salt formed when the reactants are heated at a suitable temperature for the preparation of nitric acid?
  2. State why the complete apparatus is made of glass for the preparation of nitric acid.

2. Give balanced equations for the following:                                                                                                                  [2M]

  1. Laboratory preparation of nitric acid
  2. Preparation of ethanol from monochloroethane and aq. sodium hydroxide

3. Explain the following:                                                                                                                                                [3M]

  1. Dilute nitric acid is generally considered a typical acid but not so in its reaction with metals.
  2. Concentrated nitric acid appears yellow when it is left standing in a glass bottle.
  3. An all-glass apparatus is used in the laboratory preparation of nitric acid.

4. Nitric acid is manufactured by Ostwald’s process.                                                                                                        [3M]

  1. Give the source of ammonia gas used in the manufacture.
  2. What is the ratio of ammonia to air used in the process?
  3. Which metal is used as a catalyst in Ostwald’s process?

5. Name                                                                                                                                                                       [5M]

  1. A solution which absorbs nitric oxide.
  2. A nitrate of metal which on heating does not give nitrogen dioxide.
  3. A metal nitrate which on heating is changed into metal oxide.
  4. A metal nitrate which on heating is changed into metal.
  5. A nitrate which on heating leaves no residue behind.

Chapter 11: Sulphuric Acid

1. Which property of sulphuric acid is shown by the reaction of concentrated sulphuric acid with                                          [2M]

  1. Ethanol
  2. Carbon

2.                                                                                                                                                                                 [2M]

  1. Give balanced chemical equations for the action of sulphuric acid on each of the following:
  1. Potassium hydrogen carbonate
  2. Sulphur

3. Write balanced chemical equations to show the                                                                                                             [3M]

  1. Oxidising action of conc. sulphuric acid on carbon
  2. Behaviour of H2SO4 as an acid when it reacts with magnesium
  3. Dehydrating property of conc. sulphuric acid with sugar

4. A, B, C and D summaries the properties of sulphuric acid depending on whether it is dilute or concentrated.                       [3M]
A = Typical acid property
B = Non-volatile acid
C = Oxidising agent
D = Dehydrating agent
Choose the property (A, B, C or D) depending on which is relevant to each of the following:

  1. Preparation of hydrogen chloride gas
  2. Preparation of copper sulphate from copper oxide
  3. Action of conc. sulphuric acid on sulphur

5. Give one equation each to show the following properties of sulphuric acid:                                                                       [3M]

  1. Dehydrating property
  2. Acidic nature
  3. Non-volatile acid

Chapter 12: Organic Chemistry

1. Write balanced chemical equations for the following:                                                                                                      [3M]

  1. Burning of ethane in plentiful supply of air
  2. Action of water on calcium carbide
  3. Heating of ethanol at 170°C in the presence of conc. sulphuric acid

2. Give the structural formulae for each of the following:                                                                                                    [3M]

  1. 2-methyl propane
  2. 1,2 dichloroethane
  3. butan-2-ol

3. Give balanced chemical equations for the following conversions:                                                                                      [3M]

  1. Ethanoic acid to ethyl ethanoate
  2. Acetylene to acetylene ozonide
  3. Ethene to ethylene glycol

4. A compound X (having vinegar-like smell) when treated with ethanol in the presence of acid Z gives a compound Y which has a fruity smell.                                                                                                                                                                    [3M]
The reaction is
begin mathsize 12px style straight C subscript 2 straight H subscript 5 OH plus straight x space stack rightwards arrow space with straight z on top space straight y plus straight H subscript 2 straight O end style

  1. Identify Y and Z.
  2. Write the structural formula of X.
  3. Name the above reaction.

5. Identify the term or substance based on the descriptions given below:                                                                              [4M]

  1. Ice-like crystals formed on cooling an organic acid sufficiently.
  2. Hydrocarbon containing a triple bond used for welding purposes.
  3. The property by virtue of which the compound has the same molecular formula but different structural formula.
  4. begin mathsize 12px style The space compound space formed space where space two space alkyl space groups space are space linked space by space straight a space number space stack negative large parallel to with space space space space space space straight C below and space space space space straight O on top space minus group. end style

6.                                                                                                                                                                                  [4M]

  1. Define homologous series.
  2. Complete the following table which relates to the homologous series of hydrocarbons.

Chapter 1: Periodic Table, Periodic Properties and Variations of Properties

1. Define the following terms:                                                                                                                                  [3M]

  1. Ionisation potential
  2. Electronaffinity
  3. Electronegativity
Solution:
  1. Ionisation potential: The energy required to remove an electron from a neutral isolated gaseous atom and convert it to a positively charged gaseous ion is called ionisation potential (IP) or ionisation energy (IE) or first ionisation energy (IE1).
  2. Electron affinity: The amount of energy released while converting a neutral gaseous isolated atom to a negatively charged gaseous ion(anion) by the addition of an electron is called electron affinity (EA).
  3. Electronegativity: The tendency of an atom in a molecule to attract the shared pair of electrons towards itself is called its electronegativity.

2. In Period 3 of the periodic table, Element B is placed to the left of Element A. On the basis of this information, choose the correct word from the brackets to complete the following statements:                                                                                     [3M]

  1. Element B would have (lower/higher) metallic character than Element A.
  2. Element A would probably have (lesser/higher) electron affinity than Element B.
  3. Element A would have (greater/smaller) atomic size than Element B.
Solution:
  1. Element B would have lower metallic character than Element A.
  2. Element A would probably have higher electron affinity than Element B.
  3. Element A would have smaller atomic size than Element B.

3. An element has an atomic number 16.State                                                                                                            [3M]

  1. the period to which it belongs
  2. the number of valence electrons
  3. whether it is a metal or non-metal
Solution:

Electronic configuration of sulphur is 2,8,6.

  1. Period=3
  2. Number of valence electrons=6
  3. It accepts electrons, so it is a non-metal.

4. Give reasons:                                                                                                                                                      [3M]

  1. The oxidising power of elements increases on moving from left to right along a period in the periodic table.
  2. Ionisation potential of the element increases across a period.
  3. Alkali metals are good reducing agents.
Solution:

Give reasons:

  1. Elements on the right side of the periodic table have a greater tendency to gain electrons, thereby acquiring a negative charge. So, they have a strong tendency to oxidise other elements and get reduced themselves. Thus, on moving from left to right, the tendency of gaining electrons increases and so the oxidizing power also increases.
  2. Atomic size decreases and nuclear charge increases as we move from left  to right in a period. So, the energy required to remove one electron from the valence shell increases from left to right. Thus, ionic potential increases.
  3. Alkali metals are good reducing agents because they have one valence electron which they lose to attain stability. Hence, they themselves undergo oxidation causing the reduction of others and are good reducing agents.
  4. Atom J is a Group 5 element, and a group is determined by the number of electrons present in the outermost shell.
  5. Element M from Group 7 accepts one electron to form an ion with a single negative charge.
  6. T is more reactive than R. The tendency of losing electrons increases down the group. Because chemical reactivity depends on the tendency to lose electrons, reactivity increases on going down the group.
  7. Element T has its electrons arranged in four shells. Element T belongs to Period 4 and all elements of this period have four shells.

5. Use the letters only written in the periodic table given below to answer the questions that follow:                              [4M]

  1. State the number of valence electrons in atom J.
  2. Which element as shown forms ions with a single negative charge?
  3. Which metal element is more reactive than R?
  4. Which element has its electrons arranged in four shells?
Solution:
  1. Li< Na < K < Rb < Cs
  2. Na > Mg > Si > S > Cl
  3. Na < Si < S < Cl
  4. I < Br < Cl < F

6. Arrange the following as per the instructions given in the brackets:                                                                          [4M]

  1. Cs, Na, Li, K, Rb (increasing order of metallic character)
  2. Mg, Cl, Na, S, Si (decreasing order of atomic size)
  3. Na, K, Cl, S, Si (increasing order ionisation energy)
  4. Cl, F, Br, I (increasing order of electron affinity)
Solution:
  1. Thallium
  2. Boron
  3. 3
  4. BCl3
  5. Elements in the group to the right of this boron group will be less metallic in character because, on moving to the right of the periodic table,the metallic character decreases as ionisation energy decreases and the tendency to lose electrons also decreases

7. A group of elements in the periodic table is given below: (Boron is the first member of the group and thallium is the last.)
Boron, Aluminium, Gallium, Indium, Thallium Answer the following questions in relation to the above group of elements:   [5M]

  1. Which element has the most metallic character?
  2. Which element would be expected to have the highest electronegativity?
  3. If the electronic configuration of aluminium is 2, 8, 3, how many electrons will there be in the outermost shell of thallium?
  4. The atomic number of boron is 5. Write the chemical formula of the compound formed when boron reacts with chlorine.
  5. Will the elements in the group to the right of this boron group be more metallic or less metallic in character? Justify your answer.
Solution:
  1. 30
  2. It belongs to Group 12 and the fourth period.
  3. It is a metal.
  4. The name assigned to this group is IIB.
 

Chapter 2: Chemical Bonding

1. What is the difference between                                                                                                                               [3M]

  1. Ionic compounds and polar covalent compounds
  2. Ionic compounds and covalent compounds
  3. Polar covalent compounds and non-polar covalent compounds
Solution:
  1. Ionic compounds are formed as a result of the transfer of one or more electrons from the atom of a metallic electropositive element to an atom of a non-metallic electronegative element. A polar covalent compound is one in which there is an unequal distribution of electrons between the two atoms.
  2. Ionic compounds, made of ions, are usually crystalline solids with high melting and boiling points. They are soluble in water and good conductors of electricity in the aqueous solution and molten state. Covalent compounds, made of molecules, can exist as soft solids or liquids or gases with low melting and boiling points. They are usually insoluble in water and are poor conductors of electricity.
  3. Polar covalent compounds are formed between two non-metal atoms which have different electronegativities and therefore have unequal sharing of the bonded electron pair.Non-polar compounds are formed when two identical non-metals equally share electrons.

2.                                                                                                                                                                            [3M]

  1. What are redox reactions?
  2. Why is the reaction between manganese dioxide and hydrochloric acid a redox reaction?
  3. Identify the substance oxidised and the substance reduced in the above reaction.
Solution:
  1. Reactions in which one reactant gets oxidised while the other gets reduced during the reaction are called oxidation–reduction reactions or redox reactions.
  2. The reaction between manganese dioxide and hydrochloric acid is a redox reaction because MnO2 is reduced to MnCl2 and HCl is oxidised to H2O.
  3. Oxidising agent: HCl;Reducing agent: MnO2

3.                                                                                                                                                                           [3M]

  1. State the type of bonding in the following molecules:
    a) Ammonia
    b) Calcium oxide
  2. Draw an electron dot diagram to show the formation of each of the following compounds:
  1. Methane
  2. Magnesium chloride
    [H = 1, C = 6, Mg = 12, Cl = 17]
Solution:

  1. a) Polar covalent bond
    b) Ionic bond

  2. (i) Formation of methane


    (iiI)Electron dot structure of magnesium chloride:

4. Draw the orbit structure and electron dot diagrams of                                                                                            [3M]
(i) NaCl (ii) MgCl2 (iii) CaO

Solution:

(i) Orbit structure and electron dot diagram of NaCl:


(ii) Orbit structure and electron dot diagram of MgCl2:


(iii) Orbit structure and electron dot diagram of CaO:

5. A compound has the formula H2Y (Y= non-metal). State the following:                                                                    [4M]

  1. Outer electronic configuration of Y
  2. Valency of Y
  3. Bonding present in H2Y
  4. Formula of the compound formed between calcium[20Ca 40 ] and Y
Solution:
  1. Y has six electrons in its valence shell.
  2. 2
  3. Covalent
  4. Electronic configuration of Ca=2,8,8,2
    Electronic configuration of Y=2,8,8
    Ca+2and Y−2 will form the compound CaY.

6. Predict the type of bonding in the following molecules:                                                                                            [5M]

  1. Oxygen
  2. Calcium oxide
  3. Water
  4. Methane
  5. Ammonium ion
Solution:
  1. Covalent bond
  2. Ionic bond
  3. Covalent bond
  4. Covalent bond
  5. Covalent and coordinate bond


Chapter 3: Acids, Bases and Salts

1. Give balanced chemical equations for the following:                                                                                                 [3M]

  1. Magnesium with Hydrochloric Acid
  2. Sulphuric acid with Sodium hydroxide
  3. Sodium with Sulphuric acid
Solution:
  1. Magnesium with Hydrochloric Acid
    Mg +  4HCl → MgCl2 + H2↑
    Magnesium Hydrochloric Magnesium Hydrogen Acid Chloride
  2. Sulphuric acid with Sodium hydroxide
    Dilute sulphuric acid neutralises bases (oxides and hydroxides) to form salts and water.
    2NaOH + H2SO4 → Na2SO4 + 2H2O
    Sodium hydroxide Dil. sulphuric acid Sodium sulphate Water
  3. Sodium with Sulphuric acid
    2Na + H2SO4 → Na2SO4 + H2
    Sodium  Sulphuric Acid   Sodium Sulphate   Hydrogen

2. Why don you use universal indicator, you see that solutions of different acids produce different colours. Indeed, solution of the same acid with different concentrations will also give different colours. Why?                                                                 [3M]

Solution: A universal indicator is a pH indicator made of a mixture of dyes and several compounds that shows many smooth colour changes over a wide range of pH, depending on the strength of the acid or bases. By exhibiting several colours one can determine pH of a solution ranging from 1-14. That’s also why solutions of same acid with different concentrations give different colours. The more acidic solutions turn universal indicator bright red. A less acidic solution will only turn it orange-yellow. Colour differences can be noticed in case of vinegar which is less acidic and battery acid which is more acidic.

3. Define the following as per ionic theory with examples and ionic equations wherever relevant.                                     [3M]

  1. Acid
  2. Base
  3. Alkali
Solution:
  1. Acid- An acid is a compound that dissolves in water to yield hydronium ions (H3O+
    HCl + H3O+ → H3O+ + Cl-
  2. Base- Base is a compound which reacts with hydronium ions of acid to give salt and water.
    CuO+ 2HCl→ CuCl+2H2O
  3. Alkali-An alkali is a compound which dissolved in water yields hydroxyl ions (OH- as they are negatively charged.
    NaOH(aq) → Na+(aq) + OH-

4.                                                                                                                                                                             [3M]

  1. What is the pH of pure water?
  2. What is the purpose of the pH scale?
  3. A is a soluble acidic oxide and B is a soluble base. On comparing to the pH of water, what will be the pH of solution A and solution B?
Solution:
  1. The pH of pure water is 7.
  2. It is used to determine the acidic, alkaline or neutral nature of an aqueous solution.
  3. pH<7, pH>7

5. You have been provided with three test tubes. One of them contains distilled water and the other two have an acidic solution and a basic solution respectively. If you are given red litmus paper, how will you identify the contents of each test tube?         [4M]

Solution: We know that bases turn red litmus to blue colour. So, when a drop from each of the test tubes is put on the red litmus paper the one which turns blue can be easily identified as a base. Then, the remaining test tubes contain either distilled water or acid. Now, the find out exactly the contents of these test tubes – a drop of basic solution is mixed with a drop of each of the remaining two solutions separately and then the nature of the drops of the mixtures is checked. If the colour of red litmus turns blue, then the second solution is neutral and if there is no change in colour, then the second solution is acidic. By the concept of neutralization, we know that acidic and basic solutions neutralize each other. Thus, we can distinguish between the three types of solutions and identify the contents of each test tube.

6. Give one example in each case:                                                                                                                              [5M]

  1. A basic oxide which is soluble in water.
  2. A hydroxide which is highly soluble in water.
  3. A basic oxide which is insoluble in water.
  4. A hydroxide which is insoluble in water.
  5. A weak mineral acid.
  6. A base which is not an alkali.
  7. An oxide which is a base.
  8. A hydrogen-containing compound which is not an acid.
Solution:
  1. Sodium oxide, Na2O
  2. Potassium hydroxide, KOH
  3. Copper(II) oxide, CuO
  4. Ferric hydroxide, Fe(OH)3
  5. Carbonic acid, H2CO3
  6. Copper(II) oxide, CuO
  7. Methane, CH4

7. Give one example in case-                                                                                                                                     [5M]

  1. A basic oxide which is soluble in water.
  2. A hydroxide which is highly soluble in water.
  3. A basic oxide which is insoluble in water.
  4. A hydroxide which is insoluble in water.
  5. A weak mineral acid.
  6. A base which is not alkali.
  7. An oxide which is a base.
  8. An oxide which is acid.
  9. A hydrogen containing compound which is not an acid.
  10. A base which does not contain a metal ion.

Solution:

  1. Barium oxide (BaO)
  2. Sodium hydroxide (NaOH)
  3. Manganese oxide (MnO)
  4. Copper hydroxide [Cu(OH)2]
  5. Carbonic acid (H2CO3)
  6. Ferric hydroxide [Fe(OH)3]
  7. Copper oxide (CuO)
  8. Carbon di oxide (CO2)
  9. Ammonia (NH3)
  10. Ammonium hydroxide (NH4OH)


Chapter 4: Analytical Chemistry – Use of Ammonium Hydroxide and Sodium Hydroxide

1. Identify the salts P and Q from the observations below:                                                                                          [2M]

  1. On performing the flame test, salt P produces a lilac-coloured flame and its solution gives a white precipitate with silver nitrate solution, which is soluble in ammonium hydroxide solution.
  2. When dilute HCl is added to salt Q, a brisk effervescence is produced and the gas turns limewater milky.When NH4OH solution is added to the above mixture (after adding dilute HCl), it produces a white precipitate which is soluble in excess NH4OH solution.
Solution:
  1. KCl
  2. ZnCO3

2. State your observations when ammonium hydroxide solution is added drop by drop and in excess to each of the following solutions:                                                                                                                                                                [2M]

  1. Copper sulphate solution
  2. Zinc sulphate solution
Solution:
  1. When NH4OH is added to copper sulphate solution drop-wise, a pale blue precipitate is obtained.
    CuSO4 +2NH4 OH → Cu(OH)2 +(NH4)2 SO4
    With excess of NH4OH, the precipitate dissolves to give a deep blue solution of tetrammine copper(II)sulphate.
    Cu(OH)2 +(NH4)2 SO4 +2NH4 OH → [Cu(NH3)4 ]SO4 +4H2O
  2. When NH4OH is added to zinc sulphate solution drop-wise, a white gelatinous precipitate is obtained.
    ZnSO4 +2NH4OH→ Zn(OH)2 +(NH4)2 SO4
    With excess of NH4OH, the precipitate dissolves to give a colourless solution of tetrammine zinc(II)sulphate
    Zn(OH)2 +(NH4)2 SO4 +2NH4OH → [Zn(NH3)4 ]SO4 +4H2

3. Identify the cations in each of the following cases:                                                                                                 [3M]

  1. NaOH solution when added to Solution (A) gives a reddish brown precipitate.
  2. NH4OH solution when added to Solution (B) gives a white precipitate which does not dissolve in excess.
  3. NaOH solution when added to Solution (C) gives a white precipitate which is insoluble in excess.
Solution:
  1. Fe3+ ion
    FeCl 3+3NaOH → Fe(OH)3 +3NaCl
                             (Reddish brown ppt.)
  2. Pb2+ ion
    Pb(NO3)2 +2NH4OH  → Pb(OH)2 +2NH4 NO3
                                      (chalkywhiteppt. insolublein excess)
  3. (iii) Ca2+ ion
    Ca(NO3)2 +2NaOH  → Ca(OH)2 +2NaNO3
                                    (White ppt.sparinglysoluble)

4. Give a chemical test to distinguish between the following pairs of chemicals:                                                             [4M]

  1. Lead nitrate solution and zinc nitrate solution
  2. Sodium chloride solution and sodium nitrate solution
  3. Ammonium hydroxide and sodium hydroxide
  4. Dilute sulphuric acid and dilute hydrochloric acid
Solution:
  1. Lead nitrate solution can be distinguished from zinc nitrate solution with the help of a base, i.e. NaOH. Lead nitrate gives a white precipitate of lead hydroxide on treatment with a base.
  2. To distinguish between sodium chloride and sodium nitrate, a solution of silver nitrate can be used. This gives a white precipitate with sodium chloride.
  3. Ammonium hydroxide when added to copper sulphate drop-wise forms a pale blue precipitate of copper hydroxide which dissolves in excess of ammonium hydroxide to form a deep blue solution of tetrammine copper sulphate. Sodium hydroxide when added to copper sulphate drop-wise forms a pale blue precipitate of copper hydroxide which is insoluble in excess of sodium hydroxide solution.
  4. Sulphuric acid precipitates the insoluble sulphate from lead nitrate solution. Lead nitrate reacts with hydrochloric acid to give a white precipitate of lead chloride.

5. The following table shows the test a student performed on four aqueous solutions X, Y, Z and W. Based on the observations provided, identify the  cation present:                                                                                                                         [4M]

Solution:

  1. Zn2+
  2. Cu2+
  3. Ca2+
  4. NH4+


Chapter 5: Mole Concept and Stoichiometry

1. Calculate the number of gram atoms in 4.6 grams of sodium (Na = 23)                                                                  [2M]

Solution: Given:
Mass of sodium = 4.6 g
Atomic mass of Na = 23
Number of gram atom = ?

begin mathsize 12px style No. of space gramatoms space of space Na equals fraction numerator Mass space ofNa over denominator Atomic space mass space ofNa end fraction
space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space equals space fraction numerator 4.6 over denominator 23 end fraction equals 0.2 space gmolecules space of space sodium end style

2. A gaseous hydrocarbon contains 82.76% of carbon. Given that its vapour density is 29, find its molecular formula. [C = 12, H = 11]                                                                                                                                                                      [2M]

Solution: Vapour density = 29

Empirical formula is C2H5.
Molecular weight = 2 × Vapour density
Molecular weight = n × (Empirical formula weight)
58 = n × (12 × 2 + 1 × 5)
n = 2
So, molecular formula = C4H10

3. Calculate the percentage of water of crystallization in CuSO4.5H2O
(H = 1, O = 16, S = 32, Cu = 64)                                                                                                                            [2M]

Solution: Given :
Atomic mass of H = 1
Atomic mass of O = 16
Atomic mass of S = 32
Atomic mass of Cu = 64
Molar mass of CuSO4.5H2O = (64) + (32) + (9 × 16) + (10 × 1) = 250
Molar mass of five water molecules = (10 × 1) + (5 × 16) = 90

begin mathsize 12px style space percent sign space ofwater space of space crystallisation equals 90 over 250 cross times 100
space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space equals 36 percent sign end style


4. A compound of X and Y has the empirical formula XY2. Its vapour density is equal to its empirical formula weight. Determine its molecular formula.                                                                                                                                                  [3M]

Solution: Given:
Empirical formula = XY2
Vapour density = Empirical formula weight
Molecular formula = ?
Molecular weight = n(Empirical formula weight)
= 2 × V.D.
n(Empirical formula weight) = 2 × V.D.
Since, Vapour density = Empirical formula weight
n = 2
Molecular formula = 2(Empirical formula)
= 2(XY2)
Molecular formula X2Y4

5. A cylinder contains 68 g of ammonia gas at STP.                                                                                                    [3M]

  1. What is the volume occupied by this gas?
  2. How many moles of ammonia are present in the cylinder?
  3. How many molecules of ammonia are present in the cylinder?
    [N = 14, H = 1]
Solution:
  1. Molecular weight of ammonia = 17 g/mole
    68 g of ammonia gas at STP =?
    1 mole = 22.4 dm3
    4 mole = 22.4 × 4 = 89.6 dm3
  2. 4 moles of ammonia gas is present in the cylinder.
  3. 1 mole = 6.023 × 1023 molecules
    4 moles = 24.092 × 1023 molecules

6. The mass of 11.2 litres of a certain gas at STP is 24 g. Find the gram molecular mass of the gas.                               [3M]

Solution: Given:
Volume of gas at STP = 11.2 litres
Mass of gas at STP = 24 g
Gram molecular mass = ?
The mass of 22.4 L of a gas at STP is equal to its gram molecular mass.
11.2 L of the gas at STP weighs 24 g
Therefore,
22.4 L of the gas will weigh

begin mathsize 12px style fraction numerator 24 over denominator 11.2 end fraction cross times 22.4 equals 48 straight g end style
Gram molecular mass = 48 g

7. A gas cylinder can hold 1 kg of hydrogen at room temperature and pressure.                                                            [2M]

  1. Find the number of moles of hydrogen present.
  2. What weight of CO2 can the cylinder hold under similar conditions of temperature and pressure? (Atomic masses: H = 1, C = 12, O = 16)
Solution: Given:
Mass of hydrogen = 1 kg at 298 K and 1 atm pressure
  1. Moles of hydrogen = ?
    begin mathsize 12px style space Numberofmolesofhydrogen space equals space fraction numerator Mass space of space hydrogen over denominator Gramatomic space mass space of space hydrogen end fraction
space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space equals fraction numerator 1000 straight g over denominator 1 straight g end fraction
space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space equals space 1000 space moles space of space hydrogen end style

  2. At STP, 1 mole of any gas occupies 22.4 L.
    So, at STP, 1000 moles of CO2 will occupy the same space as that of hydrogen.
    Atomic masses of C and O are 12 and 16, respectively.
    Molar mass of CO2 = 12 + 32 = 44 g
    1000 moles of CO2 = 44 × 1000 = 44000 g = 44 kg CO2
    Thus, the cylinder can hold 44 kg CO2

Chapter 6: Electrolysis

1. Give reasons why.                                                                                                                                               [3M]

  1. Sodium chloride will conduct electricity only in the fused or aqueous solution state.
  2. In the electroplating of an article with silver, the electrolyte sodium argentocyanide solution is preferred over silver nitrate solution.
  3. Although copper is a good conductor of electricity, it is a non-electrolyte.
Solution:
  1. Electrostatic forces of attraction between ions in the solid state are very strong. These forces weaken in the fused state or in the solution state. Hence, ions become mobile.
  2. If silver nitrate solution is used directly instead of double cyanide of silver and sodium, then the deposition of silver will be very fast and hence not very smooth and uniform.
  3. Copper has no mobile electrons in the solid state, and an electrolyte should dissociate into oppositely charged ions to conduct electricity. Hence, copper is a non-electrolyte.

2. Three electrolytic cells A, B and C are connected in separate circuits. Electrolytic cell A contains sodium chloride solution. When the circuit is completed, a bulb in the circuit glows brightly. Electrolytic cell B contains acetic acid solution, and here, the bulb in the circuit glows dimly. The electrolytic cell C contains sugar solution, and the bulb does not glow. Give reason for each of these observations.                                                                                                                                                            [3M]

Solution:

  1. Cell A contains sodium chloride solution which is a strong electrolyte and contains only ions. So, it conducts electricity and the bulb glows brightly.
  2. Cell B contains both ions and molecules. So, there are few ions to conduct electricity and the bulb glows dimly.
  3. Cell C contains sugar solution which is a non-electrolyte and does not contain ions. So, it is a bad conductor of electricity and the bulb does not glow.

3. State the observations at the anode and cathode during the electrolysis of                                                                  [3M]

  1. Fused lead bromide using graphite electrodes
  2. Copper sulphate solution using copper electrodes
Solution:
  1. Observations:
    Anode: Dark reddish brown fumes of bromine evolve at the anode.
    Cathode: Greyish white metal lead is formed on the cathode.
  2. Observations:
    Anode: Nothing gets deposited on the anode because the copper anode dissolves during the reaction as Cu2+ ions are formed.
    Cathode: Reddish brown Cu is deposited.

4. The following questions are related to the electroplating of an article with silver:                                                           [4M]

  1. Name the electrode formed by the article to be plated.
  2. Which ion must be present in the article to be plated?
  3. Name the electrolyte used for the electroplating of the article with silver.
  4. Give the application of electrolysis.
Solution:
  1. Cathode
  2. Silver ions/Ag+
  3. Potassium argentocyanide solution
  4. Purification of copper by electrorefining

5. Answer the following questions about the electroplating of copper wire with silver:                                                        [4M]

  1. What ions must be present in the electrolyte?
  2. Of what substance must the anode be made?
  3. What will be made the cathode?
  4. What is the equation for the reaction which takes place at the cathode?
Solution:
  1. Silver ions
  2. Pure silver
  3. Copper
  4. Ag+ e →Ag


Chapter 7: Metallurgy

1.                                                                                                                                                                               [2M]

  1. Name the most common ore of the metal aluminium from which the metal is extracted. Write the chemical formula of the ore.
  2. (Name the process by which the impure ore of aluminium is purified by using a concentrated solution of an alkali.
Solution:
 

ii. The process by which the impure ore of aluminium gets purified by using a concentrated solution of an alkali is the Bayer process.

2. Answer the following questions                                                                                                                                  [2M]

  1. Give the balanced equation for the reaction between iron oxide (III) and carbon monoxide.
  2. Explain why powdered coke is sprinkled over the electrolytic mixture.
Solution:
  1. In the manufacture of iron, a mixture of limestone, coke and iron ore is added to the blast furnace.
    begin mathsize 12px style Fe subscript 2 straight O subscript 3 plus 3 CO rightwards arrow 2 Fe plus 3 CO subscript 2 end style
  2. Powdered coke is sprinkled over the surface of the electrolytic mixture for the following reasons: 
  • Reduces heat loss by radiation
  •  Prevents burning of the anode

3. For each of the substances listed below, describe the role played in the extraction of aluminium.                                    [3M]

  1. Cryolite
  2. Sodium hydroxide
  3. Graphite 
Solution: In the extraction of aluminium, the given compounds play the following roles:
  1. Cryolite: It lowers the fusion temperature from 2050°C to 950°C and enhances conductivity.
  2. Sodium hydroxide:
    Two roles are played by sodium hydroxide in the extraction of aluminium. First, finely ground bauxite (ore of aluminium) is heated under pressure with conc. caustic soda solution (NaOH solution) for 2–8 hours at 140°C to 150°C to produce sodium aluminate. The chemical equation is as follows:
    Al2O3.2H2O + 2NaOH → 2NaAlO2 + 3H2O
    Second, on diluting sodium aluminate with water and cooling to 50°C, sodium aluminate is hydrolysed to give aluminium hydroxide as a precipitate. Here, the impurities dissolve in sodium hydroxide.
  3. Graphite: Thick rods of graphite are suspended in the fused electrolyte. They act as an anode where oxygen is discharged.

4.                                                                                                                                                                               [5M]

  1. Give the name and formula of the ore of zinc.
  2. Write equations for the following steps in the extraction of zinc:
    i. Roasting of ore
    ii. Reduction of zinc compound which is the product of the above reaction.
  3. What is add into the blast furnace in addition to zinc compound?
  4. State one large scale use of zinc.
  5. Name the process by which zinc is purified.
Solution:
  1. Zinc blende- ZnS

  2. a. 2Zns+3O2→ 2ZnO+2SO2
    b. ZnO+C→ Zn +CO
  3. Carbon
  4. Galvanisation
  5. Distillation

5. Name the following:                                                                                                                                                [4M]

  1. Process of coating of iron with zinc.
  2. Alloy of lead and tin which is used in electrical circuits.
  3. Ore of zinc containing its sulphide.
  4. Metal oxide which can be reduced by hydrogen.
Solution:
  1. Electroplating
  2. Solder
  3. Zinc blende
  4. PbO or CuO

6.                                                                                                                                                                               [4M]

  1. Name the solution used to react with bauxite as a first step in obtaining pure aluminium oxide in Bayer’s process.
  2. Write the equation for the reaction where aluminium oxide for the electrolytic extraction of aluminium is obtained by heating aluminium hydroxide.
  3. Name the compound added to pure alumina to lower the fusion temperature during the electrolytic reduction of alumina.
  4. Write the equation for the reaction which occurs at the cathode during the extraction of aluminium by electrolysis.
Solution:
  1. Conc. caustic soda
  2. Error converting from MathML to accessible text.
  3. Cryolite
  4. At the cathode: Al3+ + 3e→ Al

7. M is a metal above hydrogen in the activity series and its oxide has the formula M2O. This oxide when dissolved in water forms the corresponding hydroxide which is a good conductor of electricity. In the above context, answer the following:                 [5M]

  1. What kind of combination exists between M and O?
  2. How many electrons are there in the outermost shell of M?
  3. Name the group to which M belongs.
  4. State the reaction occurring at the cathode.
  5. Name the product at the anode
Solution:
  1. Electrovalent/ionic compound is formed.
  2. In the oxide M2O, the valency of oxygen is (-2) and the valency of M (+1).
  3. Since M has only one electron in its outermost shell, M is an alkali metal and belongs to Group 1.
  4. At the cathode: M+ + e⎺→ M …………………. Reduction
  5. Oxygen gas

Chapter 8: Hydrogen Chloride

1. For the preparation of hydrochloric acid in the laboratory:                                                                                            [2M]

  1. Why is direct absorption of hydrogen chloride gas in water not feasible?
  2. What arrangement is done to dissolve hydrogen chloride gas in water?
Solution: For the preparation of hydrochloric acid in the laboratory:
  1. Direct absorption of hydrogen chloride gas in water is not feasible because it is highly soluble in water.
  2. Hydrochloric acid is prepared by dissolving hydrogen chloride gas in water using a special funnel arrangement because direct absorption of HCl gas in water using a delivery tube causes back-suction.

2. Identify the gas evolved and give the chemical test in each of the following cases:                                                         [2M]

  1. Dilute hydrochloric acid reacts with sodium sulphite
  2. Dilute hydrochloric acid reacts with iron (II) sulphide
Solution:
  1. Sulphur dioxide
    Freshly prepared K2Cr2O7 paper changes from orange to green.
  2. Hydrogen sulphide
    The gas released has a rotten egg smell.

3. The following questions pertain to the laboratory preparation of hydrogen chloride gas:                                                  [3M]

  1. Write the equation for its preparation mentioning the condition required.
  2. Name the drying agent used and justify your choice.
  3. State a safety precaution you would take during the preparation of hydrochloric acid.
Solution:
  1. Equation for the laboratory preparation of hydrogen chloride gas:
    begin mathsize 12px style NaCl plus straight H subscript 2 SO subscript 4 space rightwards arrow with less than 200 to the power of 0 straight c on top NaHSO subscript 4 space plus HCl upwards arrow end style
    Although it is a reversible reaction, it goes to completion as hydrogen chloride continuously escapes as a gas. The reaction can occur up to the stage of the formation of sodium sulphate on heating above 200°C.
    begin mathsize 12px style NaHSO subscript 4 plus NaCl rightwards arrow with above space 200 to the power of 0 straight c on top Na subscript 2 SO subscript 4 plus HCL upwards arrow end style
  2. The drying agent used in the laboratory preparation of hydrochloric acid is conc. sulphuric acid.
    The other drying agents such as phosphorous pentoxide (P2O5) and quick lime (CaO) cannot be used because they react with hydrogen chloride.
    begin mathsize 12px style 2 straight P subscript 2 straight O subscript 5 space plus space 3 HCl space rightwards arrow space POCl subscript 3 space plus space 3 HPO subscript 3
CaO space plus space 2 HCl space rightwards arrow space POCl subscript 3 space plus space 3 HPO subscript 3 end style
  3. A safety precaution which should be taken during the preparation of hydrochloric acid: Always wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron in the laboratory during the preparation of hydrochloric acid.

4.                                                                                                                                                                                [3M]

  1. What is aqua regia?
  2. State the use of aqua regia.
  3. What is the function of HCl in the preparation of aqua regia?
Solution:
  1. Aqua regia is a mixture of three parts of conc. HCl and one part of HNO3.
  2. Uses of aqua regia: It is used for the refining of noble metals like gold and platinum.
  3. In the preparation of aqua regia, conc. HCl acts as a reducing agent

5. Study the figure given below and answer the questions which follow:                                                                             [3M]

  1. Identify gas Y.
  2. What property of gas Y does this experiment demonstrate?
  3. Name another gas with the same property which can be demonstrated by this experiment.
Solution:
  1. The gas is HCl (hydrogen chloride).
  2. The ztreme solubility of hydrogen chloride gas is demonstrated by the fountain experiment.
  3. Another gas which has the same property and can be demonstrated through this experiment is ammonia gas.


Chapter 9: Ammonia

1.                                                                                                                                                                                 [2M]

  1. State why concentrated sulphuric acid is not used for drying ammonia gas.
  2. Why is ammonia gas not collected over water?
Solution:
  1. Ammonia is basic in nature. If we use sulphuric acid as a drying agent, then it reacts with acid to give water and salt.
  2. Ammonia gas is not collected over water because it is highly soluble in water and dissolves to form ammonium hydroxide.

2. Give balanced chemical equations for each of the following:                                                                                           [3M]

  1. Laboratory preparation of ammonia using an ammonium salt
  2. Reaction of ammonia with excess chlorine
  3. Reaction of ammonia with sulphuric acid
Solution:
  1. Ammonia is prepared in the laboratory by using ammonium chloride.
    2NH4Cl + Ca(OH)2 → CaCl2 + 2H2O + 2NH3
  2. When ammonia reacts with excess of chlorine, it forms nitrogen trichloride and HCl.
    NH3 + 3Cl2 → NCl3 + 3HCl
                          (Nitrogen trichloride)
  3. Ammonia reacts with sulphuric acid to form ammonium sulphate.
    2NH3 + H2SO4 →  (NH4)2SO4
                                Ammonium sulphate

3. Explain the following:                                                                                                                                                 [3M]

  1. Dilute nitric acid is generally considered a typical acid but not so in its reaction with metals.
  2. Concentrated nitric acid appears yellow when it is left standing in a glass bottle.
  3. An all-glass apparatus is used in the laboratory preparation of nitric acid.
Solution:
  1. Dilute nitric acid is generally considered a typical acid but not in its reaction with metals because the action of nitric acid on metals depends on the temperature and concentration of nitric acid. These conditions are not required in the case of hydrochloric acid or sulphuric acid.
  2. Although pure concentrated nitric acid is colourless, it appears yellow when left standing in a glass bottle due to the dissolution of reddish brown nitrogen dioxide in the acid. Nitrogen dioxide is produced because of the thermal decomposition of a portion of nitric acid.
    4HNO3→ 2H2O + 4NO2 + O2
  3. An all-glass apparatus is used in the laboratory preparation of nitric acid because nitric acid vapour corrodes rubber and cork.

4. Give a balanced chemical equation for each of the following:                                                                                         [4M]

  1. Action of conc. nitric acid on sulphur
  2. Catalytic oxidation of ammonia
  3. Laboratory preparation of nitric acid
  4. Reaction of ammonia with nitric acid
Solution:
  1. S + 6HNO3 ¾ ¾® H2SO4 +2H2O+6NO2 
  2. 4NH3 + 5O2 ¾ ¾¾® 4NO +6H2O+Heat
  3. KNO3 + H 2SO4 ¾ ¾¾ ¾® KHSO4 +HNO3
  4. NH3 + HNO¾ ¾® NH4 NO3

 5. Give reasons for the following:                                                                                                                                   [4M]

  1. Liquid ammonia is used as a refrigerant in ice plants.
  2. Aqueous solution of ammonia is used for removing grease stains from warm clothes.
  3. Aqueous solution of ammonia gives a pungent smell.
  4. Aqueous solution of ammonia conducts electricity.
Solution:
  1. Liquid ammonia is used as a refrigerant because its latent heat of vaporisation is very high. This heat is taken from the surrounding bodies which are consequently cooled down.
  2. Aqueous solution of ammonia acts as a solvent for grease and hence cleans it.
  3. When aqueous solution of ammonium hydroxideis kept exposed to air, ammonia gas is evolved due to which it gives a pungent smell.
  4. Aqueous solution of ammonia conducts electricity due to the presence of ammonium and hydroxide ions

Chapter 10: Nitric Acid

1.                                                                                                                                                                                [2M]

  1. What is the type of salt formed when the reactants are heated at a suitable temperature for the preparation of nitric acid?
  2. State why the complete apparatus is made of glass for the preparation of nitric acid.
Solution:
  1. Potassium/sodium bisulphate is formed when potassium nitrate/sodium nitrate and conc. H2SO4 are heated at <200°C temperature for the preparation of nitric acid.
  2. For the preparation of nitric acid, the complete apparatus is made of glass. This is because nitric acid is a powerful oxidising agent, and it vigorously oxidises non-metals, metals, inorganic compounds and organic compounds.

2. Give balanced equations for the following:                                                                                                                  [2M]

  1. Laboratory preparation of nitric acid
  2. Preparation of ethanol from monochloroethane and aq. sodium hydroxide
Solution:
  1. Balanced chemical equation for the laboratory preparation of nitric acid:
    Nitric acid is prepared by the reaction of conc. sulphuric acid with potassium or sodium nitrate.
    begin mathsize 12px style KNO subscript 3 space plus space straight H subscript 2 SO subscript 4 space space rightwards arrow with less than 200 degree straight C on top space KHSO subscript 4 plus space HNO subscript 3
NaNO subscript 3 space plus space straight H subscript 2 SO subscript 4 space space rightwards arrow with less than 200 degree straight C on top space NaHSO subscript 4 space plus space HNO subscript 3 end style
  2. Balanced chemical equation for the preparation of ethanol from  monochloroethane and aqueous sodium hydroxide:
    begin mathsize 12px style straight C subscript 2 straight H subscript 5 minus Cl space plus space NaOH space left parenthesis aq. right parenthesis space rightwards arrow with boil on top straight C subscript 2 straight H subscript 5 OH space plus space NaCl end style

3. Explain the following:                                                                                                                                                [3M]

  1. Dilute nitric acid is generally considered a typical acid but not so in its reaction with metals.
  2. Concentrated nitric acid appears yellow when it is left standing in a glass bottle.
  3. An all-glass apparatus is used in the laboratory preparation of nitric acid.
Solution: An all-glass apparatus is used in the laboratory preparation of nitric acid.
  1. Dilute nitric acid is generally considered a typical acid but not in its reaction with metals, because the action of nitric acid on metals depends on the temperature and concentration of nitric acid. These conditions are not required in case of hydrochloric acid or sulphuric acid.
  2. Although pure concentrated nitric acid is colourless, it appears yellow when left standing in a glass bottle due to the dissolution of reddish brown nitrogen dioxide in the acid. Nitrogen dioxide is produced because of the thermal decomposition of a portion of nitric acid.
    4HNO3→ 2H2O + 4NO2+ O2
  3. An all-glass apparatus is used in the laboratory preparation of nitric acid because nitric acid vapour corrodes rubber and cork.

4. Nitric acid is manufactured by Ostwald’s process.                                                                                                        [3M]

  1. Give the source of ammonia gas used in the manufacture.
  2. What is the ratio of ammonia to air used in the process?
  3. Which metal is used as a catalyst in Ostwald’s process?
Solution:
  1. Ammonia gas used in the manufacture of nitric acid by Ostwald’s process is obtained by Haber’s process.
  2. 1:10
  3. Platinised wire gauge or platinum

5. Name                                                                                                                                                                       [5M]

  1. A solution which absorbs nitric oxide.
  2. A nitrate of metal which on heating does not give nitrogen dioxide.
  3. A metal nitrate which on heating is changed into metal oxide.
  4. A metal nitrate which on heating is changed into metal.
  5. A nitrate which on heating leaves no residue behind.
Solution:
  1. Ferrous sulphate solution
  2. Sodium nitrate
  3. Copper nitrate
  4. Silver nitrate
  5. Ammonium nitrate

Chapter 11: Sulphuric Acid

1. Which property of sulphuric acid is shown by the reaction of concentrated sulphuric acid with                                          [2M]

  1. Ethanol
  2. Carbon
Solution:
  1. As a dehydrating agent
  2. As an oxidising agent

2.                                                                                                                                                                                 [2M]

  1. Give balanced chemical equations for the action of sulphuric acid on each of the following:
  1. Potassium hydrogen carbonate
  2. Sulphur
Solution:
 
  1. Action of sulphuric acid on potassium hydrogen carbonate
    2KHCO3 + H2SO4→ K2SO4 + 2H2O + 2CO2
  2. Action of sulphuric acid on sulphur
    S + 2H2SO4→ 3SO2 + 2H2O

3. Write balanced chemical equations to show the                                                                                                             [3M]

  1. Oxidising action of conc. sulphuric acid on carbon
  2. Behaviour of H2SO4 as an acid when it reacts with magnesium
  3. Dehydrating property of conc. sulphuric acid with sugar
Solution:
  1. C + 2H2SO4 →CO2 + 2H2O+ 2SO2
  2. Mg + 2H2SO4 → MgSO4 + 2H2
  3. begin mathsize 12px style straight C subscript 12 straight H 22 straight O subscript 11 space rightwards arrow with straight H subscript 2 SO subscript 4 on top space 12 straight C space plus 11 straight H subscript 2 straight O end style

4. A, B, C and D summaries the properties of sulphuric acid depending on whether it is dilute or concentrated.                       [3M]
    A = Typical acid property
    B = Non-volatile acid
    C = Oxidising agent
   D = Dehydrating agent
    Choose the property (A, B, C or D) depending on which is relevant to each of the following:

  1. Preparation of hydrogen chloride gas
  2. Preparation of copper sulphate from copper oxide
  3. Action of conc. sulphuric acid on sulphur
Solution:
  1. B
  2. A
  3. C

5. Give one equation each to show the following properties of sulphuric acid:                                                                       [3M]

  1. Dehydrating property
  2. Acidic nature
  3. Non-volatile acid
Solution:

(i) Dehydrating property of sulphuric acid:
H2SO4 has a great affinity for water, and therefore, it acts as a dehydrating agent.
begin mathsize 12px style HCOOH space rightwards arrow with coc. straight H subscript 2 SO subscript 4 on top CO space plus space straight H subscript 2 straight O
straight C subscript 2 straight H subscript 5 OH rightwards arrow with coc. straight H subscript 2 SO subscript 4 on top space straight C subscript 2 straight H subscript 4 space plus straight H subscript 2 straight O end style

(ii) Acidic nature of sulphuric acid:
It acts as a strong dibasic acid.
H2SO4→ 2Hi+ + SO42−
It reacts with metals, metal oxides, metal hydroxides, carbonates etc. to form metal sulphates and hydrogen at ordinary temperature.
Mg + H2SO4→ MgSO4 + H2↑
CuO + H2SO4→ CuSO4 + H2O
2NaOH + H2SO4→ Na2SO4 + 2H2O
ZnCO3 + H2SO4→ ZnSO4 + H2O + CO2


(iii) As a non-volatile acid: It has a high boiling point, so it is used to prepare volatile acids such as HCl,
HNO3 and acetic acid from their salts.
NaCl + H2SO4→ NaHSO4 + HCl
NaNO3 + H2SO4→ NaHSO4 + HNO3
CH3COONa + H2SO4→ NaHSO4 + CH3COOH


Chapter 12: Organic Chemistry

1. Write balanced chemical equations for the following:                                                                                                      [3M]

  1. Burning of ethane in plentiful supply of air
  2. Action of water on calcium carbide
  3. Heating of ethanol at 170°C in the presence of conc. sulphuric acid
Solution:
  1. 2C2H6+7O2→4CO2+6H2O
  2. 2CaC2+2H2O→Ca(OH)2+C2H2
  3. begin mathsize 12px style 2 straight C subscript 2 straight H subscript 2 OH space rightwards arrow from 170 degree straight C to conc. straight H subscript 2 SO subscript 4 of space CH subscript 2 equals CH subscript 2 plus straight H subscript 2 straight O end style

2. Give the structural formulae for each of the following:                                                                                                    [3M]

  1. 2-methyl propane
  2. 1,2 dichloroethane
  3. butan-2-ol
Solution:






3. Give balanced chemical equations for the following conversions:                                                                                      [3M]

  1. Ethanoic acid to ethyl ethanoate
  2. Acetylene to acetylene ozonide
  3. Ethene to ethylene glycol
Solution:
begin mathsize 12px style straight i. space CH subscript 3 COOH plus straight C subscript 2 straight H subscript 5 OH rightwards arrow with Conc. straight H subscript 2 SO subscript 4 on top CH subscript 3 COOC subscript 2 straight H subscript 5 plus straight H subscript 2 straight O
ii. space HC equals space CH plus straight O subscript 3 space rightwards arrow space table row blank straight O blank blank row blank divided by backslash blank row cell straight H minus end cell cell straight C minus end cell straight C cell negative straight H end cell row blank vertical line vertical line blank row blank OH OH blank end table
iii. space CH 2 equals CH 2 plus straight H 2 straight O plus left square bracket straight O right square bracket rightwards arrow table row cell CH subscript 2 minus end cell cell CH subscript 2 end cell row vertical line vertical line row OH OH end table end style

4. A compound X (having vinegar-like smell) when treated with ethanol in the presence of acid Z gives a compound Y which has a fruity smell.                                                                                                                                                                    [3M]
The reaction is
begin mathsize 12px style straight C subscript 2 straight H subscript 5 OH plus straight x space stack rightwards arrow space with straight z on top space straight y plus straight H subscript 2 straight O end style

  1. Identify Y and Z.
  2. Write the structural formula of X.
  3. Name the above reaction.
Solution:

As compound X has vinegar-like smell, i.e. it is definitely acetic acid (CH3COOH). When treated with ethanol in the presence of acid Z, the given compound Y has a fruity smell. So, compound Y is an ester. The by-product is a water molecule, which means acid Z is a dehydrating agent, i.e. conc.
sulphuric acid (H2SO4).

  1. Y = CH3COOC2H5, Z = H2SO4
  2. Structural formula of X:

  3. Reaction:

begin mathsize 12px style stack straight C subscript 2 straight H subscript 5 OH with Erthanol below plus stack CH subscript 3 COOH rightwards arrow with blank on top with left square bracket straight X right square bracket below stack CH subscript 3 COOC subscript 2 straight H subscript 5 with left square bracket straight Y right square bracket below plus straight H subscript 2 straight O end style
The above reaction is an esterification reaction.

5. Identify the term or substance based on the descriptions given below:                                                                              [4M]

  1. Ice-like crystals formed on cooling an organic acid sufficiently.
  2. Hydrocarbon containing a triple bond used for welding purposes.
  3. The property by virtue of which the compound has the same molecular formula but different structural formula.
  4. begin mathsize 12px style The space compound space formed space where space two space alkyl space groups space are space linked space by space straight a space number space stack negative large parallel to with space space space space space space straight C below and space space space space straight O on top space minus group. end style
Solution:
  1. Glacial acetic acid
  2. Acetylene
  3. Isomerism
  4. Ketones

6.                                                                                                                                                                                  [4M]

  1. Define homologous series.
  2. Complete the following table which relates to the homologous series of hydrocarbons.

Solution:

  1. Homologous series is a series of compounds with the same functional group and similar chemical properties in which the members of the series can be branched and unbranched.




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