Assertion : `H_(2)S` is stronger acid than `PH_(3)`.
Reason : S is more electronegative than P, conjugate base`HS^(− )`is
more stable than `H_(2)P^(−)`.

Options

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

Answer

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

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that H₂S (hydrogen sulfide) is a stronger acid than PH₃ (phosphine).
- To evaluate this, we need to consider the acidic strength of both compounds.

2. **Acidic Strength Comparison**:
- Acidic strength is generally determined by the stability of the conjugate base formed after the acid donates a proton (H⁺).
- For H₂S, the conjugate base formed is HS⁻.
- For PH₃, the conjugate base formed is H₂P⁻.

3. **Analyzing the Reason**:
- The reason states that sulfur (S) is more electronegative than phosphorus (P).
- Electronegativity affects the ability of an atom to stabilize negative charge. The more electronegative an atom, the better it can stabilize a negative charge.

4. **Stability of Conjugate Bases**:
- Since sulfur is more electronegative than phosphorus, HS⁻ (the conjugate base of H₂S) is more stable than H₂P⁻ (the conjugate base of PH₃).
- A more stable conjugate base corresponds to a stronger acid. Therefore, H₂S is indeed a stronger acid than PH₃.

5. **Conclusion**:
- Both the assertion and the reason are correct. The reason correctly explains why the assertion is true, as the stability of the conjugate base is directly related to the electronegativity of the atom involved.

### Final Answer:
- Both the assertion and the reason are true, and the reason correctly explains the assertion.

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