Q4 / 100 · BITSAT 2024 (Memory Based Paper 3) · Chemistry

What would be the amount of heat absorbed in the cyclic process shown below? Figure

  • A
    $5 \pi \mathrm{~J}$
  • B
    $15 \pi \mathrm{~J}$
  • C
    $25 \pi \mathrm{~J}$
  • Correct answer
    D
    $100 \pi \mathrm{~J}$

Solution

In a cyclic process, internal energy change $=0$ According to $1^{\text {st }}$ law of thermodynamics $\Delta U=\Delta q+\Delta W$ As, $\Delta U=0, \quad \Delta q=-\Delta W$ From the graph, work done $=\Delta W=$ Area under curve Here, area of circle $=\pi r^2$ $\begin{aligned} & =\pi\left(\frac{25-5}{2}\right)^2=\pi \times 10^2 \\ \therefore \quad \Delta q & =100 \pi \mathrm{~J} \end{aligned}$

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

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