Question

A piston cylinder device initially contains 0.2 m³ neon (assume ideal) at 200 kPa insideat T₁⁰C. A valve is now opened and neon is allowed to escape until the volume reduces to half the initial volume. At the same time heat transfer with outside at T₂ ⁰C ensures a constant temperature inside. Select correct statement(s) for given process 

(A) ∆U must be zero 

(B) ∆U cannot be zero 

(C) q may be +ve 

(D) q may be –ve

Answer 1

Correct option (B, C, D)    

Explanation:

0.2 m³ Ne at 200 kP at T_i 

V_f = 1/2 VB_i = 0.1 m³

Temperature constant inside as gas volume < and pressure is constant to maintain temperature to maintain air temperature 

q may be +ve or – ve

∆V ≠ 0 as ∆ nRT ≠ 0