MCQ
To an ideal triatomic gas $800 \,cal$ heat energy is given at constant pressure. If vibrational mode is neglected, then energy used by gas in work done against surroundings is ......... $cal$
- ✓$200$
- B$300$
- C$400$
- D$60$
✓
Answer
Correct option: A.
$200$
a
(a)
(a)
Heat at constant pressure
$\Delta Q=n C_p \Delta T$
Heat for doing work
$\Delta W=n R \Delta T$
Then $\frac{\Delta W}{\Delta Q}=\frac{n R \Delta T}{n C_P \Delta T}$
$\frac{\Delta W}{800}=\left(\frac{\gamma-1}{\gamma}\right)$
$\frac{\Delta W}{800}=1-\frac{1}{\gamma}$
$\frac{\Delta W}{800}=1-\frac{3}{4}$
$\Delta W=200 \,cal$
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