Question

What is the efficiency of a carnot's engine working between ice point and steam point.

Answer 1

efficiency =  (Q1 - Q2)/Q1 =   (T1 - T2)/T1
                = (373 °K - 273° K)/373 °K
                 = 0.268

Answer 2

efficiency ={ input /out put } x 100

={(Q2 - Q1)/Q1} x 100

let Q1 , Q2 , T1 , and T2 relation in carnot engine .

Q2/Q1 =T2/T1

(Q2 - Q1 ) /Q1 = {(T2 - T1)/T1 } x 100

so,

efficiency = {(373 - 273)/373 } x 100
= 10000/373
=26.80 %