Question

A gas is compressed adiabatically. Which of the following statements is not correct? 

(1) Internal energy is constant 

(2) Temperature increases 

(3) |Work done| = |Change in internal energy| 

(4) Heat is not supplied to the system

Answer 1

(1) Internal energy is constant 

∆Q = ∆U + W

For adiabatic, ∆Q = 0 …(1) 

Also, since compression ⇒ T 

⇒ U increases.

Answer 2

When gas is compressed adiabatically, the change in internal energy is positive because internal energy is a function of temperature. Therefore, the following statement is not correct:  

(1) Internal energy is constant