ICSE Class 10 Chemistry Previous Year Question Paper 2019

Question 1

(a) Choose the correct answer from the options given below:

(i) An electrolyte which completely dissociates into ions is

A. Alcohol

B. Carbonic acid

C. Sucrose

D. Sodium hydroxide

(ii) The most electronegative element from the following elements is

A. Magnesium

B. Chlorine

C. Aluminium

D. Sulphur

(iii) The reason for using aluminium in the alloy duralumin is

A. Aluminium is brittle.

B. Aluminium gives strength.

C. Aluminium brings lightness.

D. Aluminium lowers melting point.

(iv) The drying agent used to dry HCI gas is

A. Conc. H₂SO₄

B. ZnO

C. Al₂O₃

D. CaO

(v) A hydrocarbon which is a greenhouse gas is

A. Acetylene

B. Ethylene

C. Ethane

D. Methane

(b) Fill in the blanks with the choices given in brackets:

(i) Conversion of ethanol to ethene by the action of concentrated sulphuric

acid is an example of ____________.

(dehydration/dehydrogenation/dehydrohalogenation)

(ii) When sodium chloride is heated with concentrated sulphuric acid below

200°C, one of the products formed is __________. (sodium hydrogen

sulphate/sodium sulphate/chlorine)

(iii) Ammonia reacts with excess chlorine to form _________.

(nitrogen/nitrogen trichloride/ammonium chloride)

(iv) Substitution reactions are characteristic reactions of __________.

(alkynes/alkenes/alkanes)

(v) In Period 3, the most metallic element is __________.

(sodium/magnesium/aluminium)

 

(c) Write a balanced chemical equation for each of the following reactions:

(i) Reduction of copper (II) oxide by hydrogen.

(ii) Action of dilute sulphuric acid on sodium hydroxide.

(iii) Action of dilute sulphuric acid on zinc sulphide.

(iv) Ammonium hydroxide is added to ferrous sulphate solution.

(v) Chlorine gas is reacted with ethane.

(d) State one observation for each of the following:

(i) Concentrated nitric acid is reacted with sulphur.

(ii) Ammonia gas is passed over heated copper (II) oxide.

(iii) Copper sulphate solution is electrolysed using copper electrodes.

(iv) A small piece of zinc is added to dilute hydrochloric acid.

(v) Lead nitrate is heated strongly in a test tube.

 

(e)

(i) Calculate:

1. The number of moles in 12g of oxygen gas. [O = 16]

2. The weight of 10²² atoms of carbon.

[C = 12, Avogadro’s No. = 6 x 10²³]

(ii) Molecular formula of a compound is C₆H₁₈O₃. Find its empirical formula.

 

(f)

(i) Give the IUPAC name of the following organic compounds:

1.

2.

(ii) What is the special feature of the structure of ethyne?

(iii) Name the saturated hydrocarbon containing two carbon atoms.

(iv) Give the structural formula of acetic acid.

 

(g) Give the appropriate term defined by the statements given below:

(i) The formula that represents the simplest ratio of the various elements present in one molecule of the compound.

(ii) The substance that releases hydronium ion as the only positive ion when dissolved in water.

(iii) The tendency of an atom to attract electrons towards itself when combined in a covalent compound.

(iv) The process by which certain ores, specially carbonates, are converted to oxides in the absence of air.

(v) The covalent bond in which the electrons are shared equally between the combining atoms.

 

(h) Arrange the following according to the instructions given in brackets:

(i) K, Pb, Ca, Zn (In the increasing order of reactivity)

(ii) Mg²⁺, Cu²⁺, Na¹⁺, H¹⁺ (In the order of preferential discharge at the cathode)

(iii) Li, K, Na, H (In the decreasing order of their ionisation potential)

(iv) F, B, N, O (In the increasing order of electron affinity)

(v) Ethane, methane, ethene, ethyne (In the increasing order of molecular weight) [H = 1, C = 12]

Question 2

(a) Draw the electron dot structure of

(i) Nitrogen molecule [N = 7]

(ii) Sodium chloride [Na = 11, Cl = 17]

(iii) Ammonium ion [N = 7, H = 1]

 

(b) The pH values of three solutions A, B and C are given in the table. Answer the following questions:

(i) Which solution will have no effect on litmus solution?

(ii) Which solution will liberate CO₂ when reacted with sodium carbonate?

(iii) Which solution will turn red litmus solution blue?

 

(c) Study the extract of the periodic table given below and answer the questions that follow. Give the letter corresponding to the element in question.

DO NOT repeat an element.

(i) Which element forms an electrovalent compound with G?

(ii) The ion of which element will migrate towards the cathode during electrolysis?

(iii) Which non-metallic element has the valency of 2?

(iv) Which is an inert gas?

 

Question 3

(a) Name the particles present in

(i) Strong electrolyte

(ii) Non-electrolyte

(iii) Weak electrolyte

  

(b) Distinguish between the following pairs of compounds using the reagent given in the brackets.

(i) Manganese dioxide and copper (II) oxide (using concentrated HCl)

(ii) Ferrous sulphate solution and ferric sulphate solution (using sodium hydroxide solution)

(iii) Dilute hydrochloric acid and dilute sulphuric acid (using lead nitrate solution)

 

(c) Choose the method of preparation of the following salts from the methods given in the list:

 [List:   A. Neutralisation                   B. Precipitation

         C. Direct combination          D. Substitution]

(i) Lead chloride

(ii) Iron (II) sulphate

(iii) Sodium nitrate

(iv) Iron (III) chloride

Question 4

(a) Complete the following equations:

(i) S + conc. HNO₃ →

(ii) C + conc. H₂SO⁴ →

(iii) Cu + dil. HNO₃ →

(b) Write a balanced chemical equation for the preparation of

(i) Ethene from bromoethane

(ii) Ethyne using calcium carbide

(iii) Methane from sodium acetate

(c) Name the following organic compounds:

(i) The compound with 3 carbon atoms whose functional group is carboxyl.

(ii) The first homologue whose general formula is C_nH_2n.

(iii) The compound that reacts with acetic acid to form ethyl ethanoate.

(iv) The compound formed by complete chlorination of ethyne.

Question 5

(a) Give the chemical formula of

(i) Bauxite

(ii) Cryolite

(iii) Sodium aluminate

 

(b) Answer the following question based on the extraction of aluminium from alumina by Hall-Heroult’s process:

(i) What is the function of cryolite used along with alumina as the electrolyte?

(ii) Why is powdered coke sprinkled on top of the electrolyte?

(iii) Name the electrode from which aluminium is collected.

 

(c) Match the alloys given in column I to the uses given in column II.

 

Question 6

(a) Identify the substances underlined:

(i) The catalyst used to oxidise ammonia.

(ii) The organic compound which when solidified forms an ice-like mass.

(iii) The dilute acid which is an oxidising agent.

 

(b) Copper sulphate solution reacts with sodium hydroxide solution to form a precipitate of copper hydroxide according to the equation:

2NaOH + CuSO₄ → Na₂SO₄ + Cu(OH)₂↓

(i) What mass of copper hydroxide is precipitated by using 200 gm of sodium hydroxide?

[H = 1, O = 16, Na = 23, S = 32, Cu = 64]

(ii) What is the colour of the precipitate formed?

  

(c) Find the empirical formula and the molecular formula of an organic compound from the data given below:

C = 75.92%, H = 6.32% and N = 17.76%

The vapour density of the compound is 39.5.

[C = 12, H = 1, N = 14]

 

Question 7

(a) Name the gas evolved in each of the following cases.

(i) Alumina undergoes electrolytic reduction.

(ii) Ethene undergoes hydrogenation reaction.

(iii) Ammonia reacts with heated copper oxide.

 

(b) Study the flow chart given and give balanced equations to represent the reactions A, B and C:

 

(c) Copy and complete the following table which refers to the industrial method for the preparation of ammonia and sulphuric acid:

Answer 1

(a)

(i) (D) Sodium hydroxide

(ii) (B) Chlorine

(iii) (C) Aluminium brings lightness.

(iv) (A) Conc. H₂SO₄

(v) (D) Methane

 

(b)

(i) Conversion of ethanol to ethene by the action of concentrated sulphuric acid is an example of dehydration.

(ii) When sodium chloride is heated with concentrated sulphuric acid below 200°C, one of the products formed is sodium sulphate.

(iii) Ammonia reacts with excess chlorine to form nitrogen trichloride.

(iv) Substitution reactions are characteristic reactions of alkanes.

(v) In Period 3, the most metallic element is sodium.

 

(c)

(i) Reduction of copper (II) oxide by hydrogen.

CuO_(s) + H_2(g) ⟶ Cu_(s) + 2H₂O_(I)

(ii) Action of dilute sulphuric acid on sodium hydroxide.

H₂SO₄ + 2NaOH ⟶ Na₂SO₄ + 2H₂O

(iii) Action of dilute sulphuric acid on zinc sulphide.

ZnS + H₂SO₄ ⟶ ZnSO₄ + H₂S

              (dil.)

(iv) Ammonium hydroxide is added to ferrous sulphate solution.

2NH₄OH + FeSO₄ ⟶ Fe(OH)₂ ↓ + (NH₄)₂SO₄

(v) Chlorine gas is reacted with ethane.

C₂H₆ + Cl₂ ⟶ C₂H₅Cl + HCl

 

(d)

(i) When nitric acid is added to sulphur, it gives off a deep red-orange or brown-coloured gas which has an irritating (pungent) odour.

(ii) When ammonia gas is passed over heated copper (II) oxide, black copper oxide is reduced to greyish metallic copper.

(iii) The blue colour of the copper sulphate solution remains unchanged during its electrolysis due to the copper electrodes.

(iv) When a small piece of zinc is added to dilute hydrochloric acid, white coloured zinc chloride is formed, and colourless and odourless hydrogen gas is evolved.

(v) When lead nitrate is heated strongly in a test tube, the yellow compound formed and gives off a deep red-orange or brown coloured gas which having an irritating (pungent) odour.

 

(e)

(i)

1. Given:

Mass of O₂ = 12 g

Atomic mass of O = 16

Molecular mass of O₂ = 32 g/mol

No. of moles of O₂ =?

We know,

32 g of O₂ = 1 mol

12 g of O₂ = ?

No. of moles 0.375mol

2. Given:

No. of C atoms = 10²²

We know,

1 mole of substance contains 6.022 × 10²³ atoms

6.022 × 10²³ atoms of carbon = 12 g

So, 1022 atoms of carbon

= 0.2 gm

The weight of 10²² atoms of carbon is 0.2 gm.

(ii) Molecular formula of a compound is C₆H₁₈O₃.

The ratio of elements C:H:O is 2:6:1.

Therefore, the empirical formula of the compound is C₂H₆O.

(f)

(i)

1. The IUPAC name of the compound is prpyne.

2. The IUPAC name of the compound is ethanal.

(ii) In ethyne, each carbon atom is attached to one hydrogen atom by a single covalent bond and to another carbon by a triple covalent bond.

The shape of the ethyne molecule is linear.

(iii) The saturated hydrocarbon containing two carbon atoms is ethane (C₂H₆).

(iv) The structural formula of acetic acid is

 

 

(g)

(i) Empirical formula

(ii) Acids

(iii) Electronegativity

(iv) Calcination

(v) Non-polar covalent bond

 

(h)

(i) Pb < Zn < Ca < K

(ii) Cu²⁺ > H¹⁺ > Mg²⁺ >Na¹⁺

(iii) K > Na > Li > H

(iv) B < N < O < F

(v) Methane < Ethyne < Ethene < Ethane

 

Answer 2

(a)

(i) Electron dot diagram of nitrogen molecule

(ii) Electron dot diagram of sodium chloride

(iii) Electron dot diagram of ammonium ion

 

 

(b)

(i) Solution C will have no effect on litmus solution.

(ii) Solution B will liberate CO₂ when reacted with sodium carbonate.

(iii) Solution A will turn red litmus solution blue.

 

(c)

(i) Element B forms an electrovalent compound with G.

(ii) The ion of element B (B²⁺) will migrate towards the cathode during electrolysis.

(iii) The non-metallic element which has the valency of 2 is E.

(iv) F is an inert gas.

 

Answer 3

(a)

(i) Electrolytes contain free mobile ions.

(ii) Non-electrolytes contain molecules only.

iii) Weak electrolytes contain ions as well as molecules.

 

(b)

(i) Manganese dioxide on heating with concentrated HCl gives greenish yellow chlorine gas.

Copper (II) oxide does not react with concentrated HCl.

(ii) Ferrous sulphate solution on reacting with NaOH gives green gelatinous precipitate of ferrous hydroxide Fe(OH)₂.

Ferric sulphate solution on reacting with NaOH gives a reddish brown precipitate of ferric hydroxide Fe(OH)₃.

(iii) Lead nitrate solution reacts with hydrochloric acid to give white ppt. of lead chloride.

Sulphuric acid on reacting with lead nitrate solution forms an insoluble precipitate of lead sulphate.

 

(c)

(i) Lead chloride: Precipitation

(ii) Iron (II) sulphate: Substitution

(iii) Sodium nitrate: Neutralisation

(iv) Iron (III) chloride: Direct combination

Question 4

(a)

(i) S + conc. 6HNO₃ ⟶ H₂SO₄ + 2H₂O + 6NO₂

(ii) C + conc. 2H₂SO₄ ⟶ CO₂ + 2H₂O + 2SO₂↓

 

(b)

(i) Ethene from bromoethane

(ii) Ethyne using calcium carbide

(iii) Methane from sodium acetate

 

(c)

(i) Propanoic acid

(ii) Ethene

(iii) Ethanol

(iv) Acetylene tetrachloride

 

Answer 5

(a) Chemical formula of

(i) Bauxite: Al₂O₃.2H₂O

(ii) Cryolite: Na₃AlF₆

(iii) Sodium aluminate: NaAlO₂

 

(b)

(i) Cryolite lowers the fusion temperature from 2050°C to 950°C and

enhances conductivity.

(ii) Powdered coke is sprinkled on top of the electrolyte. It reduces heat loss

by radiation. It also prevents the burning of the anode.

(iii) Aluminium is collected at the cathode.

 

(c)

Answer 6

(a)

(i) Platinum is used as a catalyst to oxidise ammonia.

(ii) Acetic acid (CH₃COOH)

(iii) Nitric acid (HNO₃)

 

(b)

(i) 2NaOH + CuSO₄ ⟶ Na₂SO₄ + Cu(OH)₂↓

       2mol         1mol       1mol           1mol

2 mol of NaOH gives a precipitate of 1 mol of Cu(OH)₂.

We know,

40 g of NaOH = 1 mol

200 g of NaOH = 5 mol

As 2 mol of NaOH gives 1 mol of Cu(OH)₂

So, 5 mol of NaOH will give

= 2.5 mol of Cu (OH)₂

1 mol of Cu(OH)₂ = 98 g

2.5 mol of Cu(OH)₂

= 245 g of Cu(OH)₂

(ii) A light blue precipitate of Cu(OH)₂ will be formed.

(c)

The empirical formula of the compound is C₅H₅N.

Empirical formula weight = 79

We know,

Molecular weight = 2 × vapour density

= 2 × 39.5

= 79

Molecular weight = n(empirical formula weight)

n = 1

Therefore, the molecular formula is C₅H₅N.

 

Answer 7

(a)

(i) Oxygen

(ii) Ethane

(iii) Nitrogen

 

(b)

A = H₂O

B = HCl

C = NaOH

 

(c)