Question

A mass of ideal gas at pressure P is expanded isothermally
to four times the original volume and then slowly
compressed adiabatically to its original volume. Assuming
g to be 1.5, the new pressure of the gas is
(a) 2 P (b) P
(c) 4 P (d) P/2

Answer 1

Answer:

the correct answer is option d

Answer 2

Answer:

Let P and V be the initial pressure and volume of ideal gas. After isothermal expansion, pressure is P/4. So volume is 4V.

Let P

1

be the pressure after adiabatic compression then

P

1

V

γ

=(P/4)(4V)

γ

P

1

=(

4

P

)(4)

3/2

=2P