Class 10 SELINA Solutions Chemistry Chapter 14 - Assertion-Reasoning Type Questions

Correct option: (c) 3

Solution:  

The second period of the periodic table consists of 8 elements namely lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, and neon. So, the assertion statement is true.

The number of elements in each period is two times the number of atomic orbitals available in the energy level that is being filled. So, the reason statement is false.

Thus, A is true but R is false.

Correct option: (d) 4

Solution:

The three elements in Dobereiner's triads are arranged so that the middle element's atomic mass equals the mean of the elements' first and last masses.

Dobereiner's law of triads states that, when elements are arranged in order of increasing atomic masses, groups of three elements(triads), having similar chemical properties are obtained. So, the reason statement, ‘Elements in a triad have similar properties’ is true.

Thus, A is false but R is true.

Correct option: (b) 2

Solution:

Electronegativity is the tendency of an atom to attract a shared pair of electrons towards itself in a molecule.

When the size of the atom decreases, the incoming electron is highly attracted towards the nucleus due to less distance as a result the electronegativity (EN) increases.

Both A and R are individually true but R is not the correct explanation of A.

Correct option: (b) 2

Solution:

The electronic configuration of hydrogen is 1s¹.

Hydrogen has one electron in its valence shell just like alkali metals or group 1 elements. Also, it exhibits similar properties to alkali metals, for example, it is a powerful reducing agent, and can give away one valence electron easily. Hence, it is placed in group 1 along with other alkali metals. So, the assertion statement is true.

Hydrogen needs just 1 electron to achieve the nearest stable noble gas configuration. So, the reason statement is also true, but it is not the correct explanation of the given assertion.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (d) 4

Solution:

Atomic size decreases along the period. So, the assertion statement is false.

Effective nuclear charge increases with an increase in atomic number across the period since the incoming electrons get added to the same period. Also, the positive charge of the nucleus increases with an increase in atomic number increasing effective nuclear charge. So, the reason statement is true.

This, A is false and R is true.

Correct option: (a) 1

Solution:

The number of electrons in the valence shell of all elements in the same group is equal or the valence shell electronic configuration is the same for the same group members. As a result, similar trends in the chemical characteristics are observed for the elements belonging to the same group.

Thus, both A and R are individually true and R is the correct explanation of A.

Correct option: (b) 2

Solution:  

The energy released when an electron is added to a neutral atom or molecule in the gaseous state to produce a negative ion is termed electron affinity. Anion formation is easier when more energy is released. So, the assertion is true.

Ionic bonding is favoured by high electron affinity.

Generally, the formation of an ionic bond is favoured by elements with a higher electron affinity since they form anions very easily and have high electronegativity values. So, the reason statement is the correct explanation of the assertion.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (a) 1

Solution:

Atoms can combine either by the transfer of valence electrons from one atom to another forming an electrovalent bond or by sharing of valence electrons forming a covalent bond. So, the assertion statement is true.

The sharing and transfer of valence electrons are done by atoms to have an octet in their valence shell to achieve the nearest noble gas stable configuration. So, the reason statement is true and is the correct explanation of the assertion statement.

Thus, both A and R are individually true and R is the correct explanation of A.

Correct option: (c) 3

Ionic or electrovalent compounds conduct electricity in a molten or aqueous state because the movement of ions is a necessary criterion for the conduction of electricity which is possible in the molten and aqueous states. So, the assertion statement is true.

Ionic or electrovalent compounds consist of positively charged cations and negatively charged anions. So, the reason statement is false.

Thus, A is true but R is false.

Correct option: (c) 3

A pair of valence shell electrons not shared with any other atom either through covalent or electrovalent bonding is known as a lone pair. So, the assertion statement is true.

In the ammonia molecule (NH₃), the nitrogen atom has a lone pair of electrons. It forms ammonium ion (NH₄⁺) by donating this lone pair of electrons to a hydrogen atom. So, the reason statement is false.

Thus, A is true but R is false.

Correct option: (d) 4

Solution:

Even if electrovalent compounds are composed of ions, for carrying electricity, the ions should be movable which is possible in the aqueous or molten state and not in a solid state. In the solid state, there are no free ions to carry the electricity, hence, electrovalent compounds do not conduct electricity in the solid state. So, the assertion statement is false but the reason statement is true.

Thus, A is false but R is true.

Correct option: (b) 2

Solution:

Acids consist of hydrogen ion (H⁺) which on dissolution in water combine with hydrogen molecules (H₂O) to form hydronium ion (H₃O⁺).

The hydrogen ion or proton cannot survive on its own in water, it joins forces with a molecule of water to produce an ion of hydronium. It is the positive ion that results from Arrhenius acid molecules in solution giving up a proton (a positive hydrogen ion, or H⁺) to the nearby water molecules (H₂O). This occurs when an Arrhenius acid is dissolved in water.

Every acid has hydrogen which on dissolution in water forms protons or hydronium ions which give acidic properties to that acid. So, the reason statement is true.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (b) 2

Solution:

An acid reacts with a base to form salt and water. This reaction is termed neutralization reaction. So, the assertion statement is true.

The bases that are soluble in water and form an aqueous solution are called alkalies. Therefore, all alkalies are bases. But, the bases that are insoluble in water cannot be termed as alkalies. So, the reason statement is true.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (c) 3

Solution:

Acids that contain carbon are necessarily organic acids except carbonic acid which is an inorganic acid. So, the assertion statement is true.

All organic acids are derived from plants. So, the reason statement is false.

Thus, A is true but R is false.

Correct option: (d) 4

Solution:

Acids have a pH of less than 7. So, the assertion statement is false.

Acids produce hydronium ions as the only positively charged ions in solution, which makes them acidic. So, the reason statement is true.

Thus, A is false but R is true.

Correct option: (a) 1

Solution:

Ferric (III) chloride solid can readily react with air moisture to generate a saturated brown-colored solution because it is hygroscopic.

Therefore, ferric (III) chloride is kept in moisture-proof containers due to its hygroscopic nature. So, both the assertion and the reason statements are true and the reason statement is the correct explanation of the assertion statement.

Thus, both A and R are individually true and R is the correct explanation of A.

Disclaimer: Incorrect answer option (c) 3 given in the textbook.

Correct option: (d) 4

Solution:

A concentrated acid and water react exothermically, which means a lot of heat is produced. When water is added to a concentrated acid, the heat produced could cause the mixture to splash out and burn people. On the other hand, the mixture won't splash out when the concentrated acid is added gradually to the water while stirring constantly. So, the assertion statement is false and the reason statement is true.

Thus, A is false but R is true.

Correct option: (a) 

Solution:  

No precipitation of calcium hydroxide (Ca(OH)₂) develops, even when additional ammonium hydroxide (NH₄OH) is added to calcium salts.

This is because the hydroxide of calcium cannot precipitate due to the extremely low concentration of hydroxide ions resulting from the ionization of NH₄OH.

Thus, A and R are individually true and R is the correct explanation of A.

Correct option: (c) 3

Solution:

A solution of ammonium hydroxide yields dirty green precipitates when iron (II) sulphate is added. Excess of these precipitates is insoluble. So, the assertion statement is true.

When ammonium hydroxide solution is added to iron (III) sulphates, reddish-brown precipitates are produced. Ferrous (Fe II) salts give green precipitates while ferric (Fe III) salts give brown precipitates. So, the reason statement is false.

Thus, A is true but R is false.

Correct option: (b) 2

Solution:

Only the metals, whose oxides/hydroxides are Amphoteric, react with strong water-soluble bases (Alkalies) to liberate hydrogen gas. Ex- Be, Zn, Al, Sn, Pb, Cr, etc.  So, the assertion statement is true.

The bases which are soluble in water are termed alkalies. So, the reason statement is true, but it is not the correct explanation for the assertion statement.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (c) 3

Oxides of most of the metals are basic in nature.

Example, sodium hydroxide [NaOH].

Not all bases are soluble in water. Only the water-soluble bases are called as alkalies.

Ferric hydroxide [Fe(OH)₃] is a base but not an alkali.

So, the reason statement is false.

Thus, A is true but R is false.

Correct option: (a) 1

Oxides of amphoteric metals such as Zinc oxide react with both acid as well as base to produce salts and water and this reaction is called neutralisation reaction.

Example,

Hydrochloric acid reacts with zinc oxide to produce zinc chloride salt and water.

Also, zinc oxide reacts with sodium hydroxide to produce sodium zincate salt and water.

So, both the assertion and the reason statements are true and the reason statement is the correct explanation of the assertion statement.

Thus, both A and R are individually true and R is the correct explanation of A.

Correct option: (a) 1

Solution:  

A certain mass of a gas occupying a volume V₁ at temperature T₁ and pressure P₁. The pressure and the temperature of the gas change from P₁ to P₂ and T₁ to T₂ respectively, so that its volume changes from V₁ to V₂.

Thus, the gas equation becomes,

P₁V₁ / T₁ = P₂V₂ / T₂

So, the assertion statement is true.

As per Boyle’s law, the change in the volume of a certain dry gas is inversely proportional to the change in the pressure.

So, P₁V₁ = P₂V₂  -----------  (i)

As per Charles’s law, the change in the volume of a certain dry gas is directly proportional to the change in the temperature.

So, V₁ / T₁ = V₂ / T₂ ----------- (ii)

 Combining both (i) and (ii) we get,

P₁V₁ / T₁ = P₂V₂ / T₂

So, the reason statement is true and it is the correct explanation of the assertion.

Thus, both A and R are individually true and R is the correct explanation of A.

Correct option: (c)

Solution:

In the Celsius scale, 0° is the freezing point of water while in the Kelvin scale, the zero point is at absolute zero. Therefore, 0°K is equal to -273.15°C and 0°C is equal to 273.15 kelvins. The Kelvin scale is used for very low or very high temperatures when water is not involved.

The absolute scale of temperature is the Kelvin scale.

Kelvin scale starts from 0°C.

Thus, A is true but R is false.

Correct option: (d)

Solution:

Triatomic molecules are molecules that are composed of three atoms, of either the same or different chemical elements.

Example: Ozone (O₃), water (H₂O).

So, the assertion statement is false.

Some elements form molecules of only one atom. Their atomicity is 1. They are called monoatomic.

Example: all noble gases are monoatomic.

So, the reason statement is true.

Thus, A is false but R is true.

Correct option: (d)

Solution:

One litre of oxygen weighs 16 times more than a litre of hydrogen, so the mass of an oxygen atom must be 16 times the mass of an atom of hydrogen.

So, the assertion statement is false.

At STP,

22.4 L of any gas = 1 mole of that gas = 6.023 × 10²³ molecules of that gas

Similarly,

1 L of any gas = 1 / 22.4 moles of that gas = 6.023 × 10²³ / 22.4 molecules of that gas

Hence,

No. of molecules in one litre of hydrogen = No. of molecules as one litre of oxygen

So, the reason statement is true.

Thus, A is false but R is true.

Correct option: (b) 2

Solution:

An atomic mass unit is a unit for expressing masses of atoms (atomic mass of an atom), molecules, or subatomic particles. So, the reason statement is true.

An atomic mass unit is equal to 1/12^th the mass of a single atom of carbon-12, the most abundant isotope of carbon. So, the reason statement is true and is the correct explanation of the assertion statement.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (b) 2

Solution:

Sulphur is an octatomic molecule.

An octatomic element is an element that, at some standard temperature and pressure, is in a configuration of eight atoms bound together (a homonuclear molecule).

The number of atoms in a molecule of an element is known as atomicity.

Atomicity is the total number of atoms present in one molecule of an element, compound or substance. In the Sulphur molecule (S₈), there are 8 atoms of oxygen.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (d) 4

One mole of any gas occupies 22.4 L at standard temperature and pressure (273 K and 1 atm). So, the assertion is false.

The mass of one mole of a gas is termed as molar mass, also called Molecular weight. So, the reason statement is true.

Thus, A is false but R is true.

Correct option: (b) 2 - Both A and R are individually true but R is not the correct explanation of A.

Solution:  

Electrolysis is where electric current is used to drive non-spontaneous reactions such as recharging a battery. In electrolysis, electrical energy is always converted to chemical energy. So, the assertion statement is true.

Metals conduct electricity in the solid state because the valence electrons of the atoms generate a mobile “sea” of electrons.

Substances that dissolve in water to form electrically conducting solutions are electrolytes. All soluble ionic compounds such as NaCl and KCl are electrolytes.

So, the reason statement is true but it is the correct explanation of the assertion.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (a) 1 - Both A and R are individually true and R is the correct explanation of A

Solution:

Benzene doesn’t dissociate at all and hence acts as a non-electrolyte. So, the assertion statement is true.

The electrons in benzene can only move within that benzene molecule. Despite being extremely mobile within the molecule, these electrons find it difficult to go on to the other molecule. Thus, benzene does not have free ions to conduct electricity. So, the reason statement is true and it is the correct explanation of the assertion statement.

Thus, both A and R are individually true and R is the correct explanation of A.

Correct option: (b) 2 - Both A and R are individually true but R is not the correct explanation of A

Solution:

Metals and alloys (solid solutions of one or more types of elements) conduct electricity in the solid state because the valence electrons of the atoms generate a mobile “sea” of electrons. So, the assertion statement is true.

Since non-metals are smaller and are arranged on the right side of the periodic table, their electrons are tightly bound to their nuclei and are not free. So, the reason statement is true but it is the correct explanation of the assertion.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (d) 4 - A is false but R is true

Solution:

Weak electrolytes allow electricity to pass through but with some resistance. So, the assertion statement is false.

Solutions containing ions conduct electricity. Solutions that contain only neutral molecules cannot conduct electricity. So, the reason statement is true.

Thus, A is false but R is true.

Correct option: (a) 1 - Both A and R are individually true and R is the correct explanation of A

Solution:

Sodium chloride solution is an ionic compound that dissociates completely in the aqueous solution into sodium and chloride ions. These ions can carry current. Hence, sodium chloride is a strong electrolyte. So, the assertion statement is true.

Sodium chloride is a nonelectrolyte in the solid state since its ions are not free. It can conduct electricity only in molten or aqueous states since in molten and aqueous states, it dissociates fully into metallic sodium ions and non-metallic chloride ions which carry electricity. So, the reason statement is true and is the correct explanation of the assertion statement.

Thus, both A and R are individually true and R is the correct explanation of A.

Correct option: (b) 2 - Both A and R are individually true but R is not the correct explanation of A

Solution:

Electrolytes are substances that, when dissolved in water, release ions. Acids, bases, and salts, all produce ions when dissolved in water. Hence, acids, bases, and salts can conduct electricity in the aqueous or molten state and so are categorized as electrolytes.

The mobility of the positive and negative ions, known as cations and anions, respectively, is what causes these solutions to conduct electricity. In a solid state, the ions of the electrolyte are not free to be mobile. The ions can be free in molten and aqueous states only.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (c) 3 - A is true but R is false

Solution:

The cathode is the negative electrode and the anode is the positive electrode in an electrolytic cell. Because opposing charges attract, this indicates that anions are drawn to the anode and cations are drawn to the cathode. Reduction occurs at the cathode while oxidation occurs at the anode.

So, the assertion statement is true.

To become neutral, anions must undergo oxidation by losing electrons, whereas cations must undergo reduction by gaining electrons. So, the reason statement is false.

Thus, A is true but R is false.

Correct option: (b) 2 - Both A and R are individually true but R is not the correct explanation of A

Solution:

Electrovalent compounds such as sodium chloride can dissolve in water since it dissociates into ions when dissolved in water.

Similarly, polar covalent compounds can conduct electricity when they are dissolved in water, as the electrons will be free to conduct electricity.

For example,

The water forms ions like H₂O → H⁺ + OH^-

HCl is a polar covalent compound when dissolved in water, the hydrogen and hydroxyl ions of water molecules break the bond between H-CI, and the ions H+ and Cl^- dissociate in water.

So, both the assertion and the reason statements are true, and the reason statement is the correct explanation of the assertion statement.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (c) 3 - A is true but R is false

Solution:

At the cathode, the cations gain electrons to form neutral atoms. As electrons are gained, the ion is said to be reduced.

At the anode, the anions lose electrons to form neutral atoms. As electrons are lost, the ion is said to be oxidized.

During electroplating with silver, the article to be electroplated serves as the cathode and a silver metal block serves as an anode where silver ions are formed which get deposited on the metal at the cathode to be plated with silver.

Thus, A is true but R is false.

Correct option: (b) 2 - Both A and R are individually true but R is not the correct explanation of A.

Solution:  

Hydrogen is a non-metal since it forms a hydride ion (H^-) by accepting an electron. It is placed above alkali metals in group 1 because, like alkali metals, hydrogen also tends to lose an electron and form a positive ion (H⁺).

So, the assertion statement is true.

All the metals whether alkali (group 1, s-block), alkaline (group 2, s-block) or transition metals (d-block), inner-transition (f-block) tend to form positive ions by donating their electrons. So, the reason statement is true but it is not the correct explanation of the assertion statement.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (c) 3 - A is true but R is false

Solution:

Alkali metals such as sodium and potassium have large size and low ionization enthalpy. Hence they can easily donate their valence shell electrons and are highly reactive.  So, the assertion statement is true.

Being highly reactive, alkali metals like sodium and potassium are not found in the elemental state or free state. So, the reason statement is false.

Thus, A is true but R is false.

Correct option: (d) 4 - A is false but R is true

Solution:

Minerals are the natural inorganic substances that exist in the earth's crust.

However, ores are the minerals from which metal can be extracted economically, profitably and conveniently. All minerals are not ores, but all ores are minerals.

So, the assertion statement is false and the reason statement is true.

Thus, A is false but R is true.

Correct option: (c) 3 - A is true but R is false

Solution:

Aluminium is extracted from its ore bauxite by electrolytic reduction. So, the assertion statement is true.

Alumina and Bauxite are the names of ores of aluminium. So, the reason statement is false.

Thus, A is true but R is false.

Correct option: (b) 2 - Both A and R are individually true but R is not the correct explanation of A.

Solution:

Metallurgy deals with the production of metals, their purification, and alloying. The various steps involved in metallurgy are:

Crushing and grinding

Concentration of the ore

Extraction of the crude metal

Purification of the metal

So, the assertion statement is true.

Reduction is one of the methods of extraction of metals.

The electrolytic reduction process is used in the extraction of the alkali and alkaline earth metals, zinc and aluminium.

Self-reduction process is used as one of the methods in metallurgy.

 The sulphide ores of less electropositive metals like Hg, Pb, Cu, etc. are heated in air to convert part of the ore into oxide or sulphate which then reacts with the remaining sulphide ore to give the metal. So, the reason statement is also true but is not the correct explanation of the assertion statement.

Thus, both A and R are individually true but R is not the correct explanation of A

Correct option: (d) 4 - A is false but R is true

Solution:

Leaching is a chemical process of concentration of aluminium ore.  So, the assertion statement is false.

The ore is dissolved in a chemical solution which can be an acid or an alkali.

The minerals react and dissolve leaving behind the impurities only. The impurities are filtered out. Finally, the metal will be obtained from the chemical solution. So, the reason statement is true.

Thus, A is false but R is true.

Correct option: (c) 3 - A is true but R is false

Solution:

Bayer's process is used for the concentration of ore in the extraction of aluminium from its main ore bauxite (Al₂O₃.2H₂O). So, the assertion statement is true.

Hoope’s electrolytic process is used for the refinement of aluminium. So, the reason statement is false.

Thus, A is true but R is false.

Correct option: (a) 1 - Both A and R are individually true but R is the correct explanation of A

Solution:

Reactive metals like calcium and magnesium are above carbon in the reactivity series. They cannot be extracted using a displacement reaction with carbon since they have a great affinity for oxygen. Therefore, reactive metals like calcium and magnesium are instead extracted using the electrolysis method, which uses electricity to break down ionic compounds into simpler substances.

So, both the assertion and the reason statement are true and the reason statement is the correct explanation of the assertion statement.

Thus, both A and R are individually true but R is the correct explanation of A.

Correct option: (a) 1 - Both A and R are individually true but R is the correct explanation of A

Solution:

Aluminum has a great affinity toward oxygen. It gets oxidized and loses its electrons to oxygen easily forming oxides. Hence, it cannot be reduced by the common reducing agent. Therefore, it is extracted from its oxide by electrolytic reduction.

So, both the assertion and the reason statements are true and the assertion statement is the correct explanation of the assertion.

Thus, both A and R are individually true but R is the correct explanation of A.

Correct option: (a) 1 - Both A and R are individually true but R is the correct explanation of A

Solution:

The material used in making electrical heating devices must have a high melting point so that they do not melt even at high temperatures when an electrical current passes through the device.

Alloys are used for electrical heating devices like electric irons and heaters because:

Alloys generally have a high melting point as compared to individual elements.

They have higher resistivity than the elements from which they are derived.

The higher resistivity is due to the additional scattering of electrons.

So, both the assertion and the reason statements are true and the reason statement is the correct explanation of the assertion statement.

Thus, both A and R are individually true but R is the correct explanation of A.

Correct option: (d) 4 - A is false but R is true

Solution:

Bronze is used in making medals, statues, etc.

Brass is hard and its flow characteristics make it a relatively easy material to cast.

Thus, A is false but R is true.

Disclaimer:

The answer option given in the solution is incorrectly given as (a)1. It should be (d)4 since brass is used in making utensils and cartridges and bronze is used in making medals and statues.

Correct option: (b) 2 - Both A and R are individually true but R is not the correct explanation of A.

Solution:

Hydrogen and chlorine undergo a combination reaction to form hydrochloric acid when exposed to sunlight. So, the assertion statement is true.

This reaction is termed a photochemical reaction.

The formation of HCl is an exothermic reaction. Hence, it is not carried out in direct sunlight as the HCl formed is protonated in the direct sunlight which can cause an explosion. So, the reason statement is true but is not the correct explanation of the assertion statement.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (c) 3 - A is true but R is false

Solution:

The Fountain experiment is used to demonstrate the high solubility of HCl gas.

Blue litmus solution turns red in the Fountain experiment.

Thus, A is true but R is false.

Correct option: (a) 1 - Both A and R are individually true and R is the correct explanation of A

Solution:

HCl gas is heavier than air. Therefore, it is collected by the upward displacement of air. The HCl gas is collected at the bottom of the container.

So, both the assertion and the reason statements are true and the reason statement is the correct explanation of the assertion statement.

Thus, both A and R are individually true and R is the correct explanation of A.

Correct option: (a) 1 - Both A and R are individually true and R is the correct explanation of A

Solution:

Hydrogen chloride gas fumes in moist air because it has high solubility in water. When the HCl gas mixes with the atmospheric vapour, it forms a mist of droplets of hydrogen chloride which appears as white fumes.

So, both the assertion and reason statements are true individually and the reason statement is the correct explanation of the assertion statement.

Thus, both A and R are individually true and R is the correct explanation of A.

Correct option: (d) 4 - A is false but R is true

Solution:

HCl gas is a polar covalent compound which on dissolution in water forms H⁺ and Cl^- ions. However, HCl cannot dissolve in organic solvents such as toluene.

Thus, A is false but R is true.

Correct option: (c)3 - A is true but R is false

Solution:

Oxidation of HCl by MnO₂ is the most common method for the laboratory preparation of chlorine gas.

Gaseous hydrogen chloride reacts with active metals and their oxides, hydroxides, and carbonates to produce corresponding chlorides.

So, the assertion statement is true.

Lead (Pb) reacts with hydrochloric acid (HCl) to form lead chloride (PbCl₂).

Pb(s)+2HCl(aq)→PbCl₂(aq)+H₂(g)

So, the reason statement is false.

Thus, A is true but R is false.

Correct option: (b) 2 - Both A and R are individually true but R is not the correct explanation of A.

Solution:

Acids have a sour taste. Being an acid, HCl has a sour taste. So, the assertion statement is true.

HCl is a polar covalent compound and forms H⁺ and Cl^- ions on dissolution in water. So, the reason statement is true but is not the correct explanation of the assertion.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (a) 1 - Both A and R are individually true and R is the correct explanation of A

Solution:  

Ammonia gas is a polar covalent compound, so it does not have any free mobile ions in its gaseous or pure liquid state, due to which it cannot conduct electricity in gaseous or liquid states.

So, both the assertion and the reason statements are true and the reason statement is the correct explanation of the assertion statement.

Thus, both A and R are individually true and R is the correct explanation of A.

Disclaimer:

In the textbook, the incorrect answer option is given as (c) – 3 A is true but R is false.

Correct option: (a) 1 - Both A and R are individually true and R is the correct explanation of A.

Solution:

Quicklime is basic and doesn't react with ammonia. Therefore, ammonia can be easily dried by passing over fresh quicklime or CaO. So, the assertion statement is true.

Ammonia being basic reacts with other drying agents such as conc, sulphuric acid, and P₂O₅.

With conc. sulphuric acid, it forms ammonium sulphate while with P₂O₅, it forms an additional product (CaCl₂.8NH₃). So, the reason statement is also true and it is the correct explanation of the assertion statement.

Thus, both A and R are individually true and R is the correct explanation of A.

Correct option: (c) 3 – A is true but R is false.

Solution:

Ammonia and ammonium salts or compounds being highly soluble in water, do not occur as minerals. So, the assertion statement is true.

Salts are ionic compounds and water is a polar covalent compound so the water molecule pulls apart the ammonium chloride lattice as a result of dipole-dipole interactions of the charged ions in the lattice. The reaction is called a hydration reaction.

For example,

Ammonia dissolves in water to form ammonium and hydroxide ions as follows:

NH₃ + H₂O ⟶ NH₄⁺ + OH^-

NH₄Cl dissolves in water to yield [NH₄⁺] and [Cl^-] ions.

The dissociation of NH₄Cl in water is as follows:

NH₄Cl_(s)⟶ NH₄⁺_(aq) + Cl^-_(aq)

So, the reason statement is false.

Correct option: (c) 3 – A is true but R is false.

Solution:

Sources of reactants for Bosch’s process are as follows:

Nitrogen gas is obtained by fractional distillation of liquid air.

Hydrogen gas is obtained from water gas (Bosch process).

So, the assertion statement is true.

The mixture of nitrogen and hydrogen used for the preparation of ammonia in Haber’s process is in the ratio of 1 volume of nitrogen to 3 volumes of hydrogen. So, the reason statement is false.

Thus, A is true but R is false.

Correct option: (c) 3 - A is true but R is false.

Solution:

Industrial production of ammonia is carried out by Haber's process. So, the assertion statement is true.

Finely divided iron is used as a catalyst in the manufacture of ammonia by Haber’s process.

So, the reason statement is false.

Thus, A is true but R is false.

Correct option: (a) 1 - Both A and R are individually true and R is the correct explanation of A.

Solution:

In Haber's process, after each cycle, the temperature of the gases is lowered. So, the pressure increases and liquefies the ammonia, while hydrogen and nitrogen remain in the gaseous state. The liquid ammonia can be separated from this mixture.

Thus, the ammonia produced in Haber’s process is liquefied to separate ammonia from uncombined nitrogen and hydrogen.

So, both the assertion and the reason statements are true and the reason statement is the correct explanation of the assertion.

Thus, both A and R are individually true and R is the correct explanation of A.

Correct option: (b) 2 – Both A and R are individually true but R is not the correct explanation of A.

Solution

Liquid ammonia takes a lot of energy to vaporise. This heat is taken from the surrounding bodies which are consequently cooled down. Thus it is used as a refrigerant in ice plants. So, the assertion statement is true.

So, the reason statement is also true but it is not the correct explanation of the assertion statement.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (b) 

Solution:  

When conc. sulphuric acid is heated with potassium nitrate, it gives nitric acid fumes and potassium bisulphate as a product.

KNO₃ + H₂SO₄  ⟶    KHSO₄ + HNO₃

Concentrated sulphuric acid is non-volatile.

So, both the assertion and the reason statements are true but the reason statement is not the correct explanation of the assertion statement.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (c)

Solution:

Concentrated nitric acid prepared in the laboratory is yellow due to the dissolution of reddish-brown coloured nitrogen dioxide gas in acid.

So, the assertion statement is true.

4HNO₃⟶ 2H₂O + 4NO₂ + O₂

Nitrogen dioxide gas is generated due to the thermal dissociation of a portion of nitric acid. So, the reason statement is false.

Thus, A is true but R is false.

Correct option: (c)

Solution:

The catalytic oxidation of ammonia to nitric oxide is an exothermic process.

Hence, the catalytic oxidation of ammonia does not require any external heat in the Oswald process. So, the assertion statement is true and the reason statement is false.

Thus, A is true but R is false.

Correct option: (a)

Solution:

The yellow colour of the acid is removed when dry air or CO₂ is bubbled through the yellow-coloured nitric acid.

The nitric acid turns colourless because it drives out NO₂ from warm acid which is further oxidized to nitric acid.

So, both the assertion and the reason statements are true and the reason statement is the correct explanation of the assertion.

Thus, both A and R are individually true and R is the correct explanation of A.

Correct option: (a) 1

Solution:

A neutralization reaction is a chemical reaction that produces salt and water as products when an acid and a base react with one another.

Water is produced during a neutralisation reaction by the interaction of H⁺ ions of acid and OH^- ions of alkali.

Thus, nitric acid reacts with NaOH/KOH to form salt and water.

So, both the assertion and the reason statements are true and the reason statement is the correct explanation of the assertion statement.

Thus, both A and R are individually true and R is the correct explanation of A.

Correct option: (a) 1

Solution:  

Sulphuric acid is known as the oil of vitriol because it looks like a dense oil and is produced from green vitriol (ferrous sulphate). So, the assertion is true.

Sulphuric acid was first discovered by heating green vitriol (FeSO₄. 7H₂O). So, the reason is also true and is the correct explanation for the assertion.

Thus, both A and R are individually true and R is the correct explanation of A.

Correct option: (b) 2

Solution:

Vanadium pentoxide is used in the contact process. It serves for the oxidation of SO₂ to SO₃ with oxygen at 440 ℃. So, the assertion statement is true.

According to the Le-Chatlier principle, exothermic reactions are favored at low temperatures. Since the catalytic oxidation of SO₂ is an exothermic reaction, it will give maximum yield at reduced temperature and high pressure.

So, the reason statement is true but not the correct explanation of the assertion statement.

Both A and R are individually true but R is not the correct explanation of A.

Correct option: (d) 4

Sulphuric acid when dissolved in water forms an acidic salt. So, the assertion statement is false. Sulphuric acid ionises in two stages since it can give two protons. Hence, it is a dibasic acid. So, the reason statement is true.

Thus, A is false but R is true.

Correct option: (b) 2

Solution:

In concentrated sulphuric acid solution, the concentration of protons or H⁺ ions is very low. Hence, concentrated sulphuric acid is a bad conductor of electricity. So, the assertion statement is true.

A large amount of H⁺ ions are produced by sulphuric acid. Hence, dilute Sulphuric acid is a good conductor of electricity. So, the reason statement is also true but not the correct explanation of the assertion.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (a) 1

The impurity of arsenic poisons the catalyst by deactivating it. So, it must be removed before passing the mixture of SO₂ air through the catalyst chamber.

So, both the assertion and reason statements are true and the reason statement is the correct explanation of the assertion.

Thus, both A and R are individually true and R is the correct explanation of A.

Correct option: (b) 2

Solution:

Concentrated sulphuric acid is a hygroscopic substance that absorbs moisture when exposed to air. Hence, it is stored in air-tight bottles.

Air contains impurities, therefore H₂SO₄ will get spoiled.

Both, the assertion and the reason statements are true but the reason statement is not the correct explanation of the assertion.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (b) 2

The chemical equation for the reaction of sulphuric acid with zinc metal is as follows:

Zn(s) + Conc. H₂SO₄ (aq) ⟶ ZnSO₄(s) + H₂(g)á

In the above reaction, the oxidation state of zinc is changing from zero to +2. Thus, concentrated sulphuric acid is oxidizing zinc metal with the release of hydrogen gas. So, both statements are true and the reason statement is the correct explanation of the assertion statement.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (b) 2

Solution:  

Carbon shows catenation because,

1. The atomic size of carbon is small.

2. The bond energy of the C – C bond is comparable with the bond energy between carbon and other element.

3. Four valence electrons are present in the outermost orbital and the tetravalency of carbon is fully saturated.

So, the assertion statement is true.

Catenation is a property by which a carbon atom can bond with any number of other carbon atoms to form straight chains, branched chains, and rings of various sizes. So, the reason statement is true but not the correct explanation of the assertion statement as the reason statement is just a definition of the term ‘catenation’.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (b) 2

Solution:

Alkynes undergo addition reactions due to the presence of loosely held pi-electrons. So, the assertion statement is true.

Hydrocarbons with only carbon-carbon single bonds are known as alkanes. They exhibit substitution reactions because they are saturated. Substitution reactions are those in which another atom or group of atoms (functional groups) replaces the hydrogen atom of an alkane. So, the reason statement is true.

Thus, both A and R are individually true but R is not the correct explanation of A.

Correct option: (c) 3

Solution:

The members of a homologous series can be prepared by using the same general method since they have the same functional group. So, the assertion statement is true.

The chemical properties of homologous series are similar since they have the same functional group. However, the physical properties of homologues are different because of increased London dispersion forces. So, the reason statement is false.

Thus, A is true but R is false.

Correct option: (c) 3

When ethylene is added to bromine water, an electrophilic addition of bromine to ethane takes place. The double bond breaks and a bromine atom becomes attached to each carbon. The bromine loses its original red-brown color to give a colorless liquid. In the case of the reaction with ethylene, 1,2-dibromoethane is formed. So, the assertion statement is true

Ethylene means the ethene compound has a C – C double bond. Hence, it can undergo an addition reaction across the double bond due to the presence of loosely held pi electrons. Substitution reaction takes place in the case of alkanes where only C – C single covalent bonds are present. So, the reason statement is false.

Thus, A is true but R is false.

Correct option: (a) 1

Solution:

Because ethyne or acetylene does not completely oxidize when burned in the air, a sooty flame is produced.

Acetylene contains a greater carbon content.

Thus, both A and R are individually true and R is the correct explanation of A.

Correct option: (a) 1

Solution:

Ethyne reacts with silver nitrate in the presence of Ammonium hydroxide to form a white precipitate of silver acetylide. So, both the assertion and reason statements are true and the reason statement if the correct explanation of the assertion statement.

Thus, both A and R are individually true and R is the correct explanation of A.

Correct option: (c) 3

Solution:

In the presence of sulphuric acid, carboxylic acid reacts with alcohol to produce an ester that has a fruity smell. So, the assertion statement is true and the reason statement is false.

Thus, A is true but R is false.