Question

A system undergoes a process in which work done by the system equals the decrease in its internal energy. The system must have undergone

• A. isothermal process
• B. isobaric process
• C. isochoric process
• D. adiabatic process

Answer 1

The correct option is D adiabatic process

According to first law of thermodynamics,
$dQ=dU+dW$
Since $dW=-dU$
$\Rightarrow dQ=0$
Hence the heat transfer across the system is zero. Therefore the process might be adiabatic.