Question

If 500 calorie of heat energy is added to a system and the system does 350 calorie of work on the surroundings, the energy change of the system is:

• A. 150 cal
• B. 850 cal
• C. -150 cal
• D. -850 cal

Answer 1

The correct option is A 150 cal

Heat absorbed, q = 500 cal; Work done by the system, w = -350 cal Applying the first law of thermodynamics,
$\Delta E=q+w=500+(-350)=150$ calorie