Saturated solution of KNO₃ is used to make 'salt-bridge' because:

1. velocity of K⁺ is greater than that of ${\mathrm{NO}}_3^{-}$

2. velocity of ${\mathrm{NO}}_3^{-}$ is greater than that of K⁺

3. Velocities of both K⁺ and ${\mathrm{NO}}_3^{-}$ are nearly the same

4. KNO₃ is highly soluble in water

When a lead storage battery is discharged, then:

1. SO₂ is evolved.

2. Lead is formed.

3. Lead sulphate is consumed.

4. Sulphuric acid is consumed.

A depolariser used in dry cell batteries is: 

1. Ammonium chloride 

2. Manganese dioxide

3. Potassium hydroxide 

4. Sodium phosphate

What happens to the voltage in a galvanic cell when the salt bridge is removed?

1. The voltage drops to zero.
2. The voltage remains the same.
3. The voltage gradually increases.
4. The voltage rapidly increases.

A device that converts energy of the combustion of fuels like hydrogen and methane, directly

into electrical energy is known as:

1. Fuel cell

2. Electrolytic cell

3. Dynamo

4. Ni-Cd cell

The efficiency of a fuel cell is given by:

1. $\frac{∆H}{∆G}$

2. $\frac{∆G}{∆S}$

3. $\frac{∆G}{∆H}$

4. $\frac{∆S}{∆G}$

In a typical fuel cell, the reactants (R) and products (P) are: 

Rusting of iron is envisaged as setting up of an electrochemical cell because: