Assertion : Equivalent weight of `Cu` in `CuO` is 63.6 and in `Cu_(2)O 31.8`.
Reason : Equivalent weight of an element `=("Atomic weight of the element")/("Valency of the element")`

Options

A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
C. If assertion is true but reason is false.
D. If assertion is false but reason is true.

Explanation

To solve the question regarding the assertion and reason provided, we will analyze both the assertion and the reason step by step.

### Step 1: Understanding the Assertion
The assertion states that the equivalent weight of copper (Cu) in CuO is 63.6 and in Cu₂O it is 31.8.

- **For CuO**:
- The molecular weight of Cu is approximately 63.5 g/mol.
- In CuO, copper has a valency of 2 (as it forms Cu²⁺).
- Therefore, the equivalent weight of Cu in CuO can be calculated as:
\[ \text{Equivalent weight} = \frac{\text{Atomic weight}}{\text{Valency}} = \frac{63.5}{2} = 31.75 \text{ g/equiv} \]
- This means the assertion that the equivalent weight of Cu in CuO is 63.6 is incorrect.

- **For Cu₂O**:
- In Cu₂O, copper has a valency of 1 (as it forms Cu⁺).
- Therefore, the equivalent weight of Cu in Cu₂O can be calculated as:
\[ \text{Equivalent weight} = \frac{63.5}{1} = 63.5 \text{ g/equiv} \]
- This means the assertion that the equivalent weight of Cu in Cu₂O is 31.8 is also incorrect.

### Step 2: Understanding the Reason
The reason states that the equivalent weight of an element is calculated using the formula:
\[ \text{Equivalent weight} = \frac{\text{Atomic weight of the element}}{\text{Valency of the element}} \]
- This formula is indeed correct and is a fundamental concept in chemistry.

### Conclusion
- Since the assertion is incorrect (the values provided for equivalent weights are wrong), but the reason is correct, we conclude that:
- **Assertion falls, Reason is true.**

### Final Answer
The correct conclusion is that the assertion is false, while the reason is true.