Q166 / 200 · Manipal (MET) 2011 · Physics

5 mol of hydrogen gas is heated from $30^{\circ} \mathrm{C}$ to $60^{\circ} \mathrm{C}$ at constant pressure. Heat given to the gas is (given $R=2 \mathrm{cal} / \mathrm{mol} \mathrm{deg}$ )

  • A
    750 cal
  • B
    630 cal
  • Correct answer
    C
    1050 cal
  • D
    1470 cal

Solution

$Q=n C_p \Delta T$ For hydrogen $C_p=\frac{7}{2} R$ So, $\begin{aligned} Q & =n \frac{7}{2} R \Delta T \\ & =5 \times \frac{7}{2} \times 2 \times 30 \\ & =1050 \mathrm{cal}\end{aligned}$

Hence, the correct answer is option: 'C'.

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