Assertion (A): s- block elements can form ionic hydrides. Which on electrolysis in fused state give `H_(2)` gas at cathode.
Reason (R) : s-block elements have low IE and low EN as compared to p-block elements.

Options

A. If both A and R are correct and R is the correct explanation for A.
B. If both A and R are correct and R is not the correct explanation for A.
C. If A is correct and R is incorrect
D. If A is incorrect and R is correct

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 "s-block elements can form ionic hydrides which on electrolysis in fused state give H2 gas at cathode."

- S-block elements (Group 1 and Group 2) indeed form ionic hydrides, such as sodium hydride (NaH) and calcium hydride (CaH2).
- When these ionic hydrides undergo electrolysis, they can release hydrogen gas. However, it is important to note that hydrogen gas is produced at the anode during the electrolysis of these hydrides, not at the cathode.

**Conclusion for Assertion (A):** The assertion is incorrect because it claims that H2 gas is produced at the cathode.

### Step 2: Analyze the Reason (R)
The reason states that "s-block elements have low ionization enthalpy and low electronegativity as compared to p-block elements."

- This statement is correct. S-block elements do have lower ionization enthalpy compared to p-block elements, which means they can easily lose electrons to form cations.
- Additionally, s-block elements are generally less electronegative than p-block elements, making it easier for them to form ionic compounds.

**Conclusion for Reason (R):** The reason is correct.

### Step 3: Determine the Relationship Between Assertion and Reason
Now, we need to evaluate the relationship between the assertion and the reason:

- The assertion is incorrect, while the reason is correct. Therefore, the reason does not provide a correct explanation for the assertion.

### Final Answer
Based on the analysis:
- Assertion (A) is incorrect.
- Reason (R) is correct.

Thus, the correct option is **4: A is incorrect and R is correct.**

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