Question

The internal energy of an ideal gas increases during an isothermal process when the gas is

• A. Expanded by adding more molecules to it
• B. Expanded by adding more heat to it
• C. Expanded against zero pressure
• D. Compressed by doing work on it

Answer 1

Answer: (A)

Expanded by adding more molecules to it

Internal energy of isotherma process

$v=\frac{f}{2}\times NKT$

$\Rightarrow v\propto NT$

T is constant (Isothermal process $v\propto N$ i.e., Internal energy increases by increasing number of molecules(N).