Assertion `(A): Cu` liberates `H_(2)(g)` from a dilute solution of `HCl`.
Reason `(R):` Hydrogen is below `Cu` in the electrochemical series.
(a)If both `(A)` and `(R)` are correct, and `(R)` is the correct explanation of `(A)`.
(b)If both `(A)` and `(R)` are correct, but `(R)` is not the correct explanation of `(A)`.
(c)If `(A)` is correct, but `(R)` is incorrect.
(d)If both `(A)` and `(R)` are incorrect.

Options

A. If both `(A)` and `(R)` are correct, and `(R)` is the correct explanation of `(A)`.
B. If both `(A)` and `(R)` are correct, but `(R)` is not the correct explanation of `(A)`.
C. If `(A)` is correct, but `(R)` is incorrect.
D. If both `(A)` and `(R)` are incorrect.

Explanation

To solve the question, we need to analyze both the assertion (A) and the reason (R) provided.

### Step 1: Analyze the Assertion (A)
The assertion states that "Cu liberates H2(g) from a dilute solution of HCl."

- **Explanation**: Copper (Cu) does not react with dilute hydrochloric acid (HCl) to liberate hydrogen gas. This is because copper is less reactive than hydrogen. In the reactivity series, hydrogen is above copper, meaning that copper cannot displace hydrogen from its compound.

### Step 2: Analyze the Reason (R)
The reason states that "Hydrogen is below Cu in the electrochemical series."

- **Explanation**: This statement is incorrect. In fact, hydrogen is above copper in the electrochemical series. This means that hydrogen is more reactive than copper, which supports the assertion that copper cannot liberate hydrogen from HCl.

### Step 3: Conclusion
Based on the analysis:
- The assertion (A) is **incorrect** because copper does not liberate hydrogen from HCl.
- The reason (R) is also **incorrect** because hydrogen is above copper in the electrochemical series.

Thus, the correct answer is:
**(d) If both (A) and (R) are incorrect.**