Question

Assertion (A): HCl gas is dried by passing through concentrated \(H_2SO_4\).
Reason (R): HCl gas reacts with \(NH_3\) that gives white fumes.

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
• B. Both (A) and (R) are correct and (R) is not the correct explanation of (A)
• C. (A) is correct but (R) is incorrect
• D. (A) is incorrect but (R) is correct

Hint:

Concentrated \(H_2SO_4\) is commonly used as a drying agent because it absorbs moisture. HCl gas gives white fumes with \(NH_3\) due to formation of solid \(NH_4Cl\).

Answer 1

The Correct Option is B

Step 1: Analyze Assertion (A).
HCl gas can be dried by passing it through concentrated sulphuric acid.
Concentrated \(H_2SO_4\) is a strong dehydrating agent and removes moisture from HCl gas.
Also, it does not react significantly with HCl gas under ordinary drying conditions.
Hence, Assertion (A) is correct.

Step 2: Analyze Reason (R).
HCl gas reacts with ammonia gas to form ammonium chloride.
The reaction is
\[ NH_3(g)+HCl(g)\rightarrow NH_4Cl(s) \] Ammonium chloride appears as dense white fumes.
Hence, Reason (R) is also correct.

Step 3: Check whether Reason explains Assertion.
The reason explains a chemical test for HCl gas, not the drying of HCl gas.
HCl is dried using concentrated \(H_2SO_4\) because \(H_2SO_4\) absorbs water.
The formation of white fumes with \(NH_3\) does not explain why concentrated \(H_2SO_4\) is used for drying HCl.

Step 4: Final conclusion.
Thus, both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
\[ \boxed{\text{Both (A) and (R) are correct and (R) is not the correct explanation of (A)}} \]