Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).

Assertion (A): Sensible heating of air increases the humidity of air.
Reason (R): Process of sensible heating is represented on the psychrometric chart by a straight horizontal line.

In light of the above statements, choose the correct answer from the options given below.

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

Hint:

"Sensible" processes mean change in temperature only with constant absolute moisture.
This translates to a horizontal line on the psychrometric chart.

Answer 1

The Correct Option is D

Step 1: Check the Assertion.
Sensible heating adds heat to air purely to raise its dry bulb temperature, without adding or removing any moisture, so the humidity ratio, that is the actual moisture content of the air, stays exactly the same. This means the claim that sensible heating increases humidity is incorrect, Assertion (A) is false.
Step 2: Check the Reason.
On a psychrometric chart, humidity ratio is read on the vertical axis. Since sensible heating changes temperature but keeps humidity ratio fixed, the process traces a straight horizontal line moving to the right at constant height on the chart, so Reason (R) is correct.
Step 3: Combine the findings.
Assertion (A) is false while Reason (R) is true.
\[ \boxed{(A) is false but (R) is true.} \]