JEE MAIN - Physics (2019 - 10th April Morning Slot - No. 14)
A cylinder with fixed capacity of 67.2 lit
contains helium gas at STP. The amount of heat
needed to raise the temperature of the gas by
20°C is : [Given that R = 8.31 J mol–1 K–1]
374 J
700 J
748 J
350 J
Explanation
$$\Delta Q = n{C_v}$$ $$\Delta T = n{3 \over 2}R\Delta T$$
$$ = \left( {{{67.2} \over {22.4}}} \right)\left( {{3 \over 2} \times 8.31} \right)\left( {20} \right)$$
$$ \approx 748\,J$$
$$ = \left( {{{67.2} \over {22.4}}} \right)\left( {{3 \over 2} \times 8.31} \right)\left( {20} \right)$$
$$ \approx 748\,J$$
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