A steam engine intakes 50g of steam at $100°C$  per minute and cools it down to $20°C.$  If latent heat of vaporization of steam is 540 cal g^-1, then the heat rejected by the steam engine per minute is………….× 10³ cal.

(Given : specific heat capacity of water : 1 cal g^{-1 0}C^-1)

$Q_1=\underset{water}{20°C}\to 100°steam$

$Q_1=mc\Delta T+mL$

$=m\left[c\Delta T+L\right]$

$=31000=31\times 10^{3}cal$

$Q_2=\frac{293}{373}\times 31\times 10^3$

$=24.35\times 10^{3}cal$

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