Chemistry NCERT Exemplar Solutions Class 12th Chapter Three

This is a Matching Type Questions as classified in NCERT Exemplar

Ans: (i)On dilution, the number of ions per unit volume increases so the molar conductivity increases with dilution.

(ii) E $°$ _cell is an intensive property as it is not dependent on the amount or mass of the substance. 

(iii) k is conductivity or be precise specific conductivity which depends on the number of ions

(iv) ΔrG_cell is an extensive property as it depends on the amount of substance or number of particles in the solution.

Hence, the answer is:

(i)-d ; (ii)a ; (iii)-b ; (iv)-c

This is a Matching Type Questions as classified in NCERT Exemplar

Ans: (i)The unit of  Λm is Scm²mol⁻¹

(ii) The unit of E_cell is m⁻¹

(iii) The unit of k is Scm⁻¹

(iv)The unit of  G∗ is m⁻¹

Hence, the answer is:

(i)-c ; (ii)-d ; (iii)-a ; (iv)-b

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: Correct Option: Option (ii, iii)

In the given representation of the cell, the left side represents the oxidation half cell and the right side of the cell represents the reduction half cell

The electrode at which oxidation occurs is called anode and oxidation of magnesium occurs at anode so magnesium is the anode.

Similarly, the electrode at which the reduction occurs is called the cathode, and the reduction of copper occurs at the cathode.

The cell reaction is as follows

Mg + Cu²⁺→Mg²⁺+ Cu

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: Correct Option: Option (i, iii)

The conductivity in an ionic solution is due to the ions in the solution. It depends on the following factors;

(a)Temperature: On an increase in temperature, the molar conductivity of ionic solutions increases.

(b)Concentration of Electrolytes: An increase in the concentration of electrolytes decreases the molar conductivity as the number of ions per unit volume decreases.

Therefore, options (i, iii) are correct

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: Correct Option: Option (i, ii)

Conductance is the reciprocal of resistance and conductivity is the reciprocal of resistivity. It can be written as follows

k = $\frac{1}{\mathbf{?}}$

R= $\mathbf{?}\mathbf{}\frac{1}{\mathbf{A}}$

$\mathbf{?}$ = $\frac{\mathbf{R}\mathbf{A}}{\mathbf{l}}$

k  = $\frac{1}{\frac{\mathbf{R}\mathbf{A}}{\mathbf{l}}}$

k = $\frac{1}{\mathbf{R}}\frac{\mathbf{l}}{\mathbf{A}}$

k = $\frac{1}{\mathbf{R}}$ G*

k = $\frac{{\mathbf{G}}^{\mathbf{*}}}{\mathbf{R}}$

G* is cell constant.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: Correct Option: Option (i, ii)

In the electrolysis process of CuSO₄ the following reactions occur at the half cell which is as follows:

At the cathode, the reaction goes this way,

Cu²⁺+2e⁻→Cu (s)

At the anode, the reaction goes this way,

Cu (s)→Cu²⁺+2e−

Here copper will be deposited at the cathode and copper will dissolve at the anode.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: Correct Option: Option (i, iii)

Electrolysis of copper sulfate solution is as follows

CuSO₄ ? Cu²⁺ + SO₄²⁻

H₂O? H⁺ + OH⁻

At the cathode, the reaction goes this way,

Cu²⁺ + 2e− → Cu; E? _Cell = 0.34V

H₂O⁻ → $\frac{1}{2}$ H₂ E? _Cell = 0.00V

At the anode, the reaction goes this way,

2SO₄^2- + 2e−→S₂O₈²⁻ E? _Cell =1.96V

2H₂O→O₂ + 4H⁺ + 4e⁻ E? _Cell =1.23V

The reaction will lower the value of E? _Cell is preferred at anode so the second reaction is feasible.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: Correct Option: Option (i, iii)

 Kohlrausch law of states that limiting molar conductivity of any salt species is equal to the sum of the limiting molar conductivity of cations and anions of the electrolyte

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: Correct Option: Option (i, ii)

Conductivity is due to the movement of ions in the solution. The conductivity of ions depends on the following factors:

(i) nature of electrolyte added

(ii) size of ion produced

(iii) concentration of electrolyte

(iv) nature of the solvent

(v) temperature

Distance between electrodes does not affect the conductivity of an electrolytic solution.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: Correct Option: Option (ii, iii)

At equilibrium, ?G $°$  = -2.303 RT ${\mathrm{l}\mathrm{o}\mathrm{g}\mathrm{K}}_{\mathrm{c}}$

-nFE $°$  = -2.303 RT ${\mathrm{l}\mathrm{o}\mathrm{g}\mathrm{K}}_{\mathrm{c}}$

E $°$ = $\frac{2.303\mathrm{}\mathrm{R}\mathrm{T}}{\mathrm{n}\mathrm{F}}{\mathrm{l}\mathrm{o}\mathrm{g}\mathrm{K}}_{\mathrm{c}}$

For Daniel cell, n=2

E $°$ = $\frac{2.303\mathrm{}\mathrm{R}\mathrm{T}}{2\mathrm{F}}{\mathrm{l}\mathrm{o}\mathrm{g}\mathrm{K}}_{\mathrm{c}}$

At equilibrium, E $°$ = 1.1V

1.1V = $\frac{2.303\mathrm{}\mathrm{R}\mathrm{T}}{2\mathrm{F}}{\mathrm{l}\mathrm{o}\mathrm{g}\mathrm{K}}_{\mathrm{c}}$

${\mathrm{l}\mathrm{o}\mathrm{g}\mathrm{K}}_{\mathrm{c}}=\mathrm{}\frac{2.2}{0.059}$

(i) Since ${\mathrm{l}\mathrm{o}\mathrm{g}\mathrm{K}}_{\mathrm{c}}=\mathrm{}\frac{2.2}{0.059}$  this option is incorrect

(ii) As derived 1.1V = $\frac{2.303\mathrm{}\mathrm{R}\mathrm{T}}{2\mathrm{F}}{\mathrm{l}\mathrm{o}\mathrm{g}\mathrm{K}}_{\mathrm{c}}$

(iii) As derived _{${\mathrm{l}\mathrm{o}\mathrm{g}\mathrm{K}}_{\mathrm{c}}=\mathrm{}\frac{2.2}{0.059}$} so this option is correct

(iv) As ${\mathrm{l}\mathrm{o}\mathrm{g}\mathrm{K}}_{\mathrm{c}}=\mathrm{}\frac{2.2}{0.059}$  _,so this option is incorrect