Question

In an attempt to demonstrate electrical conductivity through an electrolyte, the following apparatus was set up. Which among the following statement(s) is(are) correct?

1) Bulb will not glow because the electrolyte is not acidic.

2) Bulb will glow because NaOH is a strong base and furnishes ions for conduction.

3) Bulb will not glow because the circuit is incomplete.

4) Bulb will not glow because it depends upon the type of electrolytic solution.

• A. (i) and (iii)
• B. (ii) and (iv)
• C. (ii) only
• D. (iv) only

Answer 1

The correct option is C

(ii) only

Explanation for the correct option:-

Option (C):- (ii) only

• Electrical conductivity is the ability of an electrolyte to carry a current.
• Electrolyte is actually a medium which contains ions and because of the movement of those charged ions when placed in an electric field, there would be conduction of electricity.
• Electric current flows only in a closed circuit that would be formed here by the joining of two iron nails (which are the good conductor of electricity in the $\mathrm{NaOH}$ solution) with the bulb , battery and switch through the connecting wires.

• $\mathrm{NaOH}$ is a strong base and furnishes strong ${\mathrm{Na}}^{+}$ and ${\mathrm{OH}}^{-}$ ions which would be responsible for the electrical conductivity.

Explanation for the incorrect options:-

Option (A):- (i) and (iii)

• (i) - In an electrolyte bulb glows because of the ions present in the electrolyte and conduction of electricity. Both strong bases and acids are electrolytes. So bulb can glow in both, strong basic and strong acidic medium.
• (iii) - Electric current flows only in a closed circuit, here which is formed by two conducting iron nails in $\mathrm{NaOH}$ solution, 6 Volt battery, switch and bulb through the connecting wires. So the circuit is complete.

Option (B):- (ii) and (iv)

• (ii) - $\mathrm{NaOH}$ is a strong base which will furnish ions for the conduction for electricity, Therefore, bulb will glow in $\mathrm{NaOH}$ solution.
• (iv) - Bulb depends on the conducting ions present in the electrolytic solution. And in this strong $\mathrm{NaOH}$ solution, ions are present for the conduction and bulb's glow.

Option (D):- (iv)

• Bulb depends upon the ions present in the electrolytic solution and in this $\mathrm{NaOH}$ solution, strong ${\mathrm{Na}}^{+}$ and ${\mathrm{OH}}^{-}$ ions are present, because of which there would be flow of current in the closed circuit.

Therefore, the correct option is (C), Bulb will glow because NaOH is a strong base and furnishes ions for conduction.