Find the change in internal energy of the system when a system absorbs 2 kilo-calorie of heat and at the same time does 500 joules of work
(A) 7900 J
(B) 8200 J
(C) 5600 J
(D) 6400 J
Answer is (A) 7900 J
Heat supplied is 2 kcal, 2 kcal = 2000 x 4.2 = 8400 joules. Energy consumed in doing work = 500 joules. Increase I internal energy = 8400 – 500 = 7900 joules.
