Question

A Carnot cycle is having an efficiency of 0.75. If the temperature of the high temperature reservoir is 727 C, what is the temperature of low temperature reservoir? (a) 23°C(b) -23°C (c) 0°C(d) 250°C

Answer 1

Efficiency for any Heat engine = Work done by engine / Heat provided to the engine

Also, for a carnot engine derived formula for Carnot Engine
= 1- T2/T1
Where, T2 = sink reservoir temperature
and T1 = source reservoir temperature
727° C = 1000 K
So,
0.75 = 1-T2 / 1000
So,
T2 = 1000*0.25 = 250 K = -23 Kelvin

So, option (B) is correct

Hope this helps you !