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Standard XII

Chemistry

Second Law of Thermodynamics

A heat engine...

Question

A heat engine receives 800 W heat at 870 K and reject 500 W to the ambient at 300 K. The ratio of first law efficiency to second law efficiency is

0.72

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0.42

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0.65

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0.35

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Solution

The correct option is C 0.65
$η_{I I} = \frac{η_{I}}{η_{c a n n o t}}$

$η_{c a n n o t} = \frac{η_{I}}{η_{I I}} = (1 - \frac{T_{o}}{T})$

$= (1 - \frac{300}{870}) = 0.65$

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A heat engine receives 800 W heat at 870 K and reject 500 W to the ambient at 300 K. The ratio of first law efficiency to second law efficiency is

The correct option is C 0.65ηII=ηIηcannot ηcannot=ηIηII=(1−ToT) =(1−300870)=0.65

The correct option is C 0.65
$η_{I I} = \frac{η_{I}}{η_{c a n n o t}}$

$η_{c a n n o t} = \frac{η_{I}}{η_{I I}} = (1 - \frac{T_{o}}{T})$

$= (1 - \frac{300}{870}) = 0.65$