When a gas expands adiabatically

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

A balloon filled with helium $\left(32^{\circ} C \right.$ and $1.7\; atm$.) bursts. Immediately afterwards the expansion of helium can be considered as

In the reported figure, there is a cyclic process $ABCDA$ on a sample of $1\, {mol}$ of a diatomic gas. The temperature of the gas during the process ${A} \rightarrow {B}$ and ${C} \rightarrow {D}$ are ${T}_{1}$ and ${T}_{2}\left({T}_{1}\,>\,{T}_{2}\right)$ respectively.

Choose the correct option out of the following for work done if processes $B C$ and $D A$ are adiabatic.

The $PV$ diagram shows four different possible reversible processes performed on a monatomic ideal gas. Process $A$ is isobaric (constant pressure). Process $B$ is isothermal (constant temperature). Process $C$ is adiabatic. Process $D$ is isochoric (constant volume). For which process$(es)$ does the temperature of the gas decrease?