Electrochemistry(12th Grade > Chemistry ) Questions and answers for exam Preparation

12th Grade > Chemistry

ELECTROCHEMISTRY MCQs

Total Questions : 30 | Page 3 of 3 pages

Question 21. Which of the following statement(s) is(are) true?
A. The conductance of an electrolyte is dependent on the nature of the electrolyte.
B. Conductance of a solution equals the inverse of resistivity of the solution.
C. In an electrolytic cell the flow of electrons is from cathode to anode.

A, B
A,C
Only A
Only C

Discuss Question

Answer: Option C. -> Only A
:
C
Conductance of a solution equals the inverse of resistance of the solution, and not the resistivity
In an electrolytic cell the cathode acts as the source of electrons, hence the flow of electrons is from anode to cathode.

Question 22. The specific conductance of

\frac{N}{10} K C l

solution at

20^{\circ} C

0.0212 o h m^{- 1} c m^{- 1}

and the resistance of cell containing this solution at

20^{\circ} C

is 55 ohm. The cell constant is

1.166 cm−1
2.173 cm−1
3.324 cm−1
4.616 cm−1

Discuss Question

Answer: Option A. -> 1.166 cm−1
:
A

K = \frac{1}{R} \times c e l l c o n s t a n t

Cell constant

= K \times R = 0.0212 \times 55 = 1.166 c m^{- 1}

Question 23. On passing one faraday of electricity through the electrolytic cells containing

A g^{+}, N i^{+ 2}

and

C r^{+ 3}

ions solution, the deposited

A g (A t . w t . = 108), N i (A t . w t . = 59) a n d C r (A t . w t . = 52)

\begin{matrix} A g (i n g m) & N i (i n g m) & C r (i n g m) a) & 108 & 59 & 52 b) & 108 & 29.5 & 17.3 c) & 36 & 19.6 & 17.3 d) & 108 & 108 & 108 \end{matrix}

Discuss Question

Answer: Option B. -> b
:
B
Wt. of Ag deposited = Equivalent weight of Ag

= \frac{108}{1} = 108 g m

Wt. of Ni deposited = Equivalent weight of Ni

= \frac{59}{2} = 29.5 g m

Wt. of Cr deposited = Equivalent weight of Cr

= \frac{52}{3} = 17.3 g m

Question 24. The standard electrode potentials of

\frac{Z n^{2 +}}{Z n}

and

\frac{A g^{+}}{A g}

are

- 0.763 V

and

+ 0.799 V

respectively. The standard potential of the cell is

1.562 V
2.361 V
−1.562 V
−2.361 V

Discuss Question

Answer: Option A. -> 1.562 V
:
A

E_{c e l l}^{\circ} = E_{c a t h o d e}^{\circ} - E_{a n o d e}^{\circ} = 0.799 - (- 0.763) = 1.562 V

Question 25. Which of the following represents the anode half-cell reaction for the following galvanic cell:

C u (s) | C u^{2 +} (a q) | | A g^{+} (a q) | A g (s)

Cu(s)+2Ag+(aq)→Cu2+(aq)+2Ag(s)
Cu(s)→Cu2+(aq)+2e−
2Ag+(aq)+2e−→2Ag(s)
Ag+(aq)+e−→Ag(s)

Discuss Question

Answer: Option B. -> Cu(s)→Cu2+(aq)+2e−
:
B
Reduction reaction takes place at cathode and oxidation reaction takes place at anode.
Cathode

: 2 A g^{+} (a q) + 2 e^{-} \to 2 A g (s)

Anode

: C u (s) \to C u^{2 +} (a q) + 2 e^{-}

Cell reaction

: C u (s) + 2 A g^{+} (a q) \to C u^{2 +} (a q) + 2 A g (s)

Question 26. The hydrogen electrode is dipped in a solution of

p H = 3

25^{\circ} C

. The potential of the cell would be (the value of

2.303 \frac{R T}{F}

0.059 V

0.177 V
−0.177 V
0.087 V
0.059 V

Discuss Question

Answer: Option B. -> −0.177 V
:
B
Reduction potential of hydrogen electrode

= E_{H} = \frac{- 2.303 R T}{F} l o g \frac{1}{[H^{+}]} = - 0.059 p H = - 0.059 \times 3 = - 0.177 V

Question 27. During the electrolysis of an electrolyte, the number of ions produced is dependent on

Temperature
Nature of solvent
Nature of the electrolyte
All of the above

Discuss Question

Answer: Option D. -> All of the above
:
D
Number of ions produced depends on degree of dissociation, which depends on factors like nature of electrolyte, nature of solvent, temperature etc.

Question 28. Which of the following conversion takes place in a galvanic cell?

Electrical energy to chemical energy
Chemical energy to electrical energy
Chemical energy to mechanical energy
Mechanical energy to chemical energy

Discuss Question

Answer: Option B. -> Chemical energy to electrical energy
:
B
A galvanic cell is an electrochemical cell that converts the chemical energy of a spontaneous redox reaction to the electrical energy.

Question 29. What amount of current is required to be passed during a period of 5 minutes in order to deposit 0.6354gm of copper by electrolysis of aqueous cupric sulphatesolution? (Molar wt. of Copper = 63.5gm/mole)