Question

If the work done by the system is 300 Joule when 100 calorie heat is supplied to it. The change in internal energy during the process is:

• A. -200 Joule
• B. 400 Joule
• C. 720 Joule
• D. 120 Joule

Answer 1

The correct option is D 120 Joule

Solution:- (D) $120J$

As the work is done by the system and heat is supplied to the system.

Therefore,

$q=100\text{cal}=420J$

$w=-300J$

Now from first law of thermodynamics,

$\Delta U=q+W$

$\therefore \Delta U=420+(-300)=120J$

Hence the internal energy change during the process is $120J$.