Thermodynamics - Result Question 5
5. The internal energy change in a system that has absorbed 2 kcals of heat and done $500 J$ of work is:
(a) $6400 J$
(b) $5400 J$
(c) $7900 J$
(d) $8900 J$
[2009]
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Answer:
Correct Answer: 5. (c)
Solution:
- (c) According to first law of thermodynamics
$Q=\Delta U+W$
$\Delta U=Q-W$
$=2 \times 4.2 \times 1000-500=8400-500$
$=7900 J$
