Question

Find the change in internal energy of the system when a system absorbs 2 kilocalorie of heat and at the same time does 500 joule of work

• A. 7900 J
• B. 8200 J
• C. 5600 J
• D. 6400 J

Answer 1

The correct option is A 7900 J

$△Q=2Kcal=2\times {10}^3\times 4.2J=8400J$ and $△W=500J$
Hence from $△Q=△U+△W,△W=△Q-△U=8400-500=7900J$