Question

Helium gas goes through a cycle ABCDA (consisting of two isochoric and two isobaric lines) as shown in figure. Efficiency of this cycle is nearly (Assume the gas to be close to ideal gas)

(a) 9.1%

(b) 10.5%

(c) 12.5% 

(d) 15.4%

Answer 1

(d) : In case of a cyclic process, work done is equal to the area under the cycle and is taken to be positive if the cycle is clockwise.
∴ Work done by the gas
W = Area of the rectangle ABCD = P₀V₀
Helium gas is a monoatomic gas.