Statement-I: In electrolysis the quantity needed for depositing 1 mole of silver is different from that required for 1 mole of copper.
Because Statement-II: The molecular weights of silver and copper are different.

Answer

To analyze the statements provided in the question, we will break down the reasoning step by step.

### Step-by-Step Solution:

1. **Understanding Electrolysis**:
Electrolysis is a process that uses electrical energy to drive a non-spontaneous chemical reaction. In electrolysis, ions in a solution are reduced or oxidized at the electrodes.

**Hint**: Remember that electrolysis involves the movement of ions towards electrodes where reduction and oxidation occur.

2. **Analyzing Statement-I**:
The first statement claims that the quantity needed for depositing 1 mole of silver (Ag) is different from that required for 1 mole of copper (Cu).

- For silver (Ag), which typically exists in the +1 oxidation state, the reduction reaction can be represented as:
\[ \text{Ag}^+ + e^- \rightarrow \text{Ag} \]
This indicates that 1 mole of Ag requires 1 mole of electrons (or 1 Faraday of charge).

- For copper (Cu), which usually exists in the +2 oxidation state, the reduction reaction is:
\[ \text{Cu}^{2+} + 2e^- \rightarrow \text{Cu} \]
This shows that 1 mole of Cu requires 2 moles of electrons (or 2 Faradays of charge).

Therefore, the quantity of charge required for depositing 1 mole of silver is indeed different from that required for 1 mole of copper.

**Hint**: Compare the number of electrons needed for the reduction of each metal to see the difference.

3. **Analyzing Statement-II**:
The second statement claims that the molecular weights of silver and copper are different, which is presented as a reason for the first statement being true.

- While it is true that silver and copper have different molecular weights, this difference does not directly relate to the quantity of charge required for deposition during electrolysis. The key factor is the number of electrons involved in the reduction of each metal ion.

- The requirement of different moles of electrons for the deposition of Ag and Cu is based on their oxidation states, not their molecular weights.

**Hint**: Focus on the relationship between oxidation states and the number of electrons needed, rather than molecular weights.

4. **Conclusion**:
- Statement-I is true because different moles of electrons are required for the deposition of silver and copper.
- Statement-II is not a valid reason for Statement-I being true, as the difference in molecular weights does not influence the electrolysis process.

### Final Answer:
- Statement-I is true.
- Statement-II is false as a reason for Statement-I.