Question

A gas can be taken from A to B via two different processes ACB and ADB. When path ACB is used, \( 60 J \) of heat flows into the system and \( 30 J \) of work is done by the system. If path ADB is used, the work done by the system is \( 10 J \). The heat flow into the system in path ADB is: 
 

• A. \( 40 J \)
• B. \( 80 J \)
• C. \( 100 J \)
• D. \( 20 J \)

Hint:

Change in internal energy \( \Delta U \) depends only on initial and final states, not on the path.

Answer 1

The Correct Option is A

Step 1: {Using first law of thermodynamics}
\[ \Delta Q = \Delta U + \Delta W \] Step 2: {For process ACB}
\[ \Delta U = 60 - 30 = 30 J \] Step 3: {Applying same internal energy change to ADB}
\[ \Delta Q_{ADB} = 30 + 10 = 40 J \] Thus, the correct answer is \( 40 J \).