A heat engine having an efficiency of 70% is used to drive

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A heat engine having an efficiency of 70% is used to drive a refrigerator having a coefficient of performance of 5. The energy absorbed from low temperature reservoir by the refrigerator for each kJ of energy absorbed from high temperature source by the engine is

1. 0.14kJ
2. 0.71kJ
3. 3.5 kJ
4. 7.1 kJ

Correct Option: C

Given: η_engine = 0.7, (C.O.P)_R = 5

η_engine =	W	...(i)
	Q₁

Now,

(C.O.P)_R =	Q₂
	W

∴ W =	Q₂	...(ii)
	5

Again,

0.7 =	Q₂	×	1
	5		Q₁

or	Q₂	= 3.5
	Q₁

Energy absorbed from low temperature reservoir by the refrigerator for each kJ of energy absorbed from high temperature source by the engine = 3.5 kJ.