`1 g` mole of an ideal gas at STP is subjected to a reversible adiabatic expansion to double its volume. Find the change in internal energy `( gamma = 1.4)`

Options

A. 1169 J
B. 769 J
C. 1373 J
D. 969 J

Answer

B

Explanation

For adiabatic expansion
`T_(1)V_(1)^(gamma-1)=T_(2)V_(2)^(gamma-1)`
`T_(2)=T_(1)(V_(1))/(V_(2))^(gamma-1)=273((1)/(2))^(1.4-1)=206 K`
dU =dW =`(R )/(gamma-1)(T_(1)-T_(2))`
`=(1xx8.31)/(1.4-1)(273-206.89)=1373 J`