Electrochemistry MCQs

Question 1

In which of the following electrochemical cell, overall cell reaction is: HgO(s) + H2 (g) → Hg(l) + H2O(l) ?

Accepted Answer

Mercury cell

Answer

Alkaline battery

Answer

Lead-acid battery

Answer

Fuel cell

Question 2

Faraday's law of electrolysis are related to the:

Accepted Answer

Equivalent mass of the electrolyte

Answer

Atomic number of the cation

Answer

Atomic number of anion

Answer

Speed of the cation

Question 3

The reaction occurring at anode when the electrolysis of an aqueous solution containing Na2SO4 and CuSO4 is done using Pt electrode is:

Accepted Answer

oxidation of water to form oxygen gas and hydrogen ions.

Answer

Oxidation of copper ions to form copper oxide

Answer

Oxidation of sulfate ions to form sulfur trioxide

Answer

Oxidation of chloride ions to form chlorine gas

Question 4

During electrolysis, the gm of product produced (m) and when plotted against the electric charge Q′ in faradays, which of the following plot is correct?

Accepted Answer

Option B: A straight line with a positive slope passing through the origin

Answer

Option A: A horizontal line

Answer

Option C: A curve that starts at the origin and curves upwards

Answer

Option D: A straight line with a negative slope

Question 5

Which of the following is not correct for dry cell?

Accepted Answer

NH3 gas is liberated out

Answer

Zinc is used as anode

Answer

Manganese is reduced from + 4 to + 3 state

Answer

It is a primary cell

Question 6

Two half cells have reduction potentials − 0.76 V and −0.13 V respectively. A galvanic cell is made from these two half cells. Which of the following statements is correct?

Accepted Answer

Electrode of half-cell potential − 0.76 V serve as anode

Answer

Electrode of half-cell potential − 0.76 V serves as cathode

Answer

Electrode of half-cell potential − 0.13 V serves as anode

Answer

Electrode of half-cell potential − 0.76 V serves as positive electrode and -0.13 V as negative electrode

Question 7

Beryllium is placed above magnesium in the II group. Beryllium dust, therefore, when added to MgCl2 solution will:

Accepted Answer

Have no effect

Answer

Precipitate Mg metal

Answer

Precipitate MgO

Answer

Lead to dissolution of Be metal

Question 8

3 faraday of electricity is passed through molten Al2O3 , aqueous solution of CuSO4 and molten NaCl taken in three different electrolytic cells. The amount of Al, Cu and Na deposited at the cathodes will be in the ratio of:

Accepted Answer

1 mole : 1.5 mole : 3 mole

Answer

1 mole : 2 mole : 3 mole

Answer

3 mole : 2 mole : 1 mole

Answer

1.5 mole : 2 mole : 3 mole

Question 9

Which statement is not correct for Kohlrausch law?

Accepted Answer

The law is valid for weak electrolytes only

Answer

The law is valid at infinite dilution

Answer

The basis of the law is independent migration of ions

Answer

None of the above

Question 10

In the equation ∧m = ∧°m − Ac 1/2, the constant 'A' depends on :

Accepted Answer

All of these

Answer

Nature of solvent

Answer

Temperature

Answer

Type of electrolyte

Question 11

The standard reduction potentials at 298 K for the following half reactions are given against each. Which is the strongest reducing agent?

Accepted Answer

Zn(s)

Answer

Cr(s)

Answer

H2(g)

Answer

Fe2+(aq)

Question 12

Chromium plating of an article was carried out by treating it as cathode in an electrolysis. If during electrolysis the weight of the article increased by 2.6 g and 0.56 dm3 of oxygen (corrected up to STP) evolves at inert anode, the oxidation state of the chromium ions being discharged must be:

Accepted Answer

+2

Answer

+1

Answer

+3

Answer

+6

Question 13

Three faradays of charge is passed through an aqueous solution of NaClO3 when NaClO4 is formed according to the reaction: NaClO3 + H2O → NaClO4 + H2How many moles of NaClO4 will be formed during the electrolysis?

Accepted Answer

1.5

Answer

0.75

Answer

1.0

Answer

3.0

Question 14

In the electrolysis of CuCl2 solution using Cu electrodes, the weight of Cu anode increased by 2 gram at cathode. In the anode,

Accepted Answer

2 gram of copper goes into solution as Cu2+

Answer

0.2 mole of Cu2+ will go into solution

Answer

560 ml O2 is liberated

Answer

No loss in weight

Question 15

Electrolysis of dil H2SO4 liberates gases at anode and cathode:

Accepted Answer

O2 & H2 respectively

Answer

O2 & SO2 respectively

Answer

SO2 & O2 respectively

Answer

H2 & O2 respectively

Question 16

Electrolysis of a solution MnSO4 in aqueous sulphuric acid is a method for the preparation of MnO2 passing a current of 27 A for 24 hours gives 1 kg of MnO2 .The current efficiency is:

Accepted Answer

95.185%

Answer

100%

Answer

80%

Answer

82.951%

Question 17

At 25ºC, the standard emf of cell having reactions involving two electron change is found to be 0.295 V. The equilibrium constant of the reaction is:

Accepted Answer

1010

Answer

29.5 x 10^-2

Answer

10

Answer

29.5 x 10^10

Question 18

The number of faradays required to produce one mole of water from a hydrogen - oxygen fuel cell containing aqueous alkali as electrolyte is:

Accepted Answer

2

Answer

1

Answer

3

Answer

4

Question 19

During discharge of a lead storage cell the density of sulphuric acid in the cell:

Accepted Answer

Decreases

Answer

Increases

Answer

Remains unchanged

Answer

Initially increases but decreases subsequently

Question 20

F2 gas can't be obtained by the electrolysis of any F- salt because:

Accepted Answer

Fluorine is the strongest oxidising agent

Answer

Fluorine is the strongest reducing agent

Answer

Fluorine easily combines with atmospheric O2

Answer

All

Free Electrochemistry MCQs with Answers