Thermodynamics Ques 5
5. The volume $(V)$ of a monatomic gas varies with its temperature (T), as shown in the graph. The ratio of work done by the gas, to the heat absorbed by it, when it undergoes a change from state A to state B, is
[2018]
(a) $\frac{2}{5}$
(b) $\frac{2}{3}$
(c) $\frac{2}{7}$
(d) $\frac{1}{3}$
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Answer:
Correct Answer: 5.(a)
Solution:
- (a) Gas is monatomic, so $C_p=\frac{5}{2} R$
Given process is isobaric
$\therefore dQ=nC_p dT$
$\Rightarrow dQ=n(\frac{5}{2} R) d T$
$dW=PdV=n$ RdT
$\therefore \quad$ Required ratio $=\frac{d W}{d Q}=\frac{n R d T}{n(\frac{5}{2} R) d T}=\frac{2}{5}$
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