Can a change in the internal energy of an ideal gas be considered an adiabatic process?

Does the internal energy of an ideal gas change in an adiabatic process?

$A$ gas is being compressed adiabatically. The specific heat of the gas during compression is

An ideal gas having initial pressure $P$, volume $V$ and temperature $T$ is allowed to expand adiabatically until its volume becomes $4V$, while its temperature falls to $T/2$. If the work done by the gas during the expansion is $\alpha PV$, the value of $\alpha$ is

$5.6 \ L$ of helium gas at $STP$ is adiabatically compressed to $0.7 \ L$. If the initial temperature of the gas is $T \ K$,the work done in the process is ($R$ is the universal gas constant in $SI$ units).

Which of the following statements is true? ($\Delta U = \text{increase in internal energy}$,$dW = \text{work done by the system}$)