Following are statements of a few processes taking place in nature:
$I$. Free expansion of a gas
$II$. The combustion of a mixture of petrol and air ignited by a spark
$III$. The leaking of gas from the kitchen cylinder
$IV$. The transfer of heat from one heated part of a liquid to the other colder part
Which amongst these processes are irreversible in nature?

What is a quasi-static process?

For a reversible process,the necessary condition is:

For the free expansion of a gas,which of the following is true?

Given below are two statements. One is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A) :$ In an insulated container,a gas is adiabatically shrunk to half of its initial volume. The temperature of the gas decreases.
Reason $(R) :$ Free expansion of an ideal gas is an irreversible and an adiabatic process.
In the light of the above statement,choose the correct answer from the options given below :

Consider the given diagram. An ideal gas is contained in a chamber (left) of volume $V$ and is at an absolute temperature $T$. It is allowed to rush freely into the right chamber of volume $V$ which is initially vacuum. The whole system is thermally isolated. What will be the final temperature once the equilibrium has been attained?