Question

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): A gas stream, the so-called carrier gas, is fed into the column at a constant rate.
Reason (R): The carrier gas is chemically inert and is generally nitrogen or helium.
In the light of the above statements, choose the most appropriate answer from the options given below :

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

Hint:

GC → Constant gas flow for separation; inert gas (He, N₂) prevents chemical reactions.

Answer 1

The Correct Option is B

Concept: Gas Chromatography (GC) is an analytical technique where a gaseous mobile phase (carrier gas) transports analytes through a column containing the stationary phase.

Step 1: Analyzing Assertion (A).
In GC, the carrier gas must flow at a constant and controlled rate to ensure:
• Reproducible retention times
• Proper separation of components
• Stable baseline during detection Thus, Assertion (A) is correct.

Step 2: Analyzing Reason (R).
Carrier gases such as nitrogen, helium, or hydrogen are used because they are chemically inert and do not react with analytes or stationary phase.
Thus, Reason (R) is also correct.

Step 3: Evaluating relationship.
Although both statements are correct:
• Assertion explains the requirement of constant flow.
• Reason explains the chemical nature of the gas. The inert nature of the gas does not explain why constant flow is required.

Step 4: Final evaluation.
Thus, both (A) and (R) are correct, but (R) is not the correct explanation of (A). Final Conclusion:
Hence, the correct answer is option (2).