Two electrolytic cells,one containing acidified ferrous chloride and another acidified ferric chloride, are connected in series. The ratio of iron deposited at cathodes in the two cells will be :

3 : 1
2 : 1
1 : 1
3 : 2

Solution

Solution

During charging, the lead storage battery behaves like an electrolytic cell. So,at anode the reaction is
PbSO₄ + 2H₂O ⟶ PbO₂ + 4H⁺ + \(So_{4}^{2-}\) + 2e^-

In a hydrogen-oxygen fuel cell, combustion of hydrogen occurs to

produce high purity water
create potential difference between two electrodes
generate heat
remove adsorbed oxygen from elctrode surfaces

Solution

In H₂ -O₂ fuel cell, the combustion of H₂ occurs to create potential difference between the two electrodes.

Several blocks of magnesium are fixed to the bottom of a ship to

make the ship lighter
prevent action of water and salt
prevent puncturing by under-sea rocks
keep away the sharks

Solution

Magnesium provides cathodic protection and prevent rusting or corrosion

A certain current liberated 0.504 gm of hydrogen in 2 hrs.How many grams of copper can be liberated by the same current flowing for the same time in a copper sulphate solution ?

12.7 gms
15.9 gms
31.8 gms
63.5 gms

Solution

The most durable metal plating on iron to protect against corrosion is

nickel plating
copper plating
tin plating
zinc plating

Solution

This is because zinc has higher oxidation potential than Ni, Cu and Sn. The process of coating of iron surface with zinc is known as galvanization. Galvanized iron sheets maintain their lustre due to the formation of protective layer of basic zinc carbonate.

For the cell reaction,Cu²⁺(C₁, aq) + Zn(s) = Zn²⁺(C₂, aq) + Cu(s) of an electrochemical cell, the change in free energy, ΔG, at a given temperature is a function of

ln(C₁)
ln(C₂/C₁)
ln (C₂)
ln(C₁ + C₂)

Solution

The quantity of electricity needed to liberate 0.5 gram equivalent of an element is

48250 faraday
48250 coulomb
19300 faraday
19300 coulomb

Solution

Electricity required = No. of g equiv.× 96500 coulombs= 0.5 × 96500 = 48250 C

An electrochemical cell is set up as: Pt; H₂(1 atm)|HCl(0.1M)|| CH₃COOH (0.1 M)| H₂(1 atm); Pt. The e.m.f of this cell will not be zero, because

the temperature is constant
e.m.f depends on molarities of acids used
acids used in two compartments are different
pH of 0.1 M HCl and 0.1 M COOHCH₃ is not same

Solution

Standard cell voltage for the cell Pb | Pb²⁺|| Sn²⁺ | Sn is– 0.01 V. If the cell is to exhibit E_cell = 0, the value of[Sn²⁺] / [Pb²⁺] should be antilog of –

+ 0.3
0.5
1.5
– 0.5

Solution

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