Thermodynamics Ques 8

8. Figure below shows two paths that may be taken by a gas to go from a state $A$ to a state $C$.

In process $A B,$ $ 400$ $ J$ of heat is added to the system and in process $BC, $ $100 $ $J$ of heat is added to the system. The heat absorbed by the system in the process $AC$ will be

[2015]

(a) $500$ $ J$

(b) $460$ $ J$

(c) $300$ $ J$

(d) $380$ $ J$

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Answer:

Correct Answer: 8.(b)

Solution:

  1. (b) In cyclic process $ABCA$

$ Q _{\text{cycle }}=W _{\text{cycle }} $

$Q _{AB}+Q _{BC}+Q _{CA}=$ ar. of $\triangle ABC$ $+400+100+Q _{C \to A}=\frac{1}{2}(2 \times 10^{-3})(4 \times 10^{4})$

$\Rightarrow Q _{C \to A} = - 460$ $ J$

$\Rightarrow Q _{C \to A} = + 460$ $J$