MCQ
When an ideal gas in a cylinder was compressed isothermally by a piston, the work done on the gas was found to be $1.5 \times {10^4}\;joules$. During this process about
  • $3.6 \times {10^3}$ cal of heat flowed out from the gas
  • B
    $3.6 \times {10^3}$ cal of heat flowed into the gas
  • C
    $1.5 \times {10^4}$ cal of heat flowed into the gas
  • D
    $1.5 \times {10^4}$ cal of heat flowed out from the gas

Answer

Correct option: A.
$3.6 \times {10^3}$ cal of heat flowed out from the gas
a
(a)In isothermal compression, there is always an increase of heat. which must flow out the gas.
$\Delta Q = \Delta U + \Delta W \Rightarrow \Delta Q = \Delta W\;\;(\because \;\Delta U = 0)$
==> $\Delta Q = - 1.5 \times {10^4}J = \frac{{1.5 \times {{10}^4}}}{{4.18}}cal = - 3.6 \times {10^3}cal$

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