The quantity of silver deposited when one coulomb charge is passed through AgNO₃ solution :

Solution

Chemistry ma’am · 4 steps

Electrochemical equivalent means the mass that one coulomb deposits, so this is its definition.

1. Faraday's first law. The mass deposited is proportional to the charge passed: m = ZQ. The constant Z is the electrochemical equivalent of the substance.
2. Put in one coulomb. With Q = 1 C, the law gives m = Z. So one coulomb deposits exactly one electrochemical equivalent of silver.

   Z_(Ag) = (108 g mol⁻¹)/(1 × 96500 C mol⁻¹) ≈ 1.12 × 10⁻³ g C⁻¹

3. Check the others. One chemical equivalent of silver is 108 g and needs a full faraday, 96500 C. The amounts 0.1 g atom (10.8 g) and 1 g are far larger than the 0.00112 g that one coulomb gives.
4. So. One coulomb deposits 1 electrochemical equivalent of silver, option (d).

The idea to keep. Electrochemical equivalent goes with 1 coulomb. Chemical (gram) equivalent goes with 1 faraday, 96500 C. Keep these two pairs straight and such questions are free marks.

Answer from the NTA final answer key. Solution by PrepWiser.