Which process is acceptable in nature: a reversible or an irreversible process?

Write a short note on reversible and irreversible processes.

In a thermodynamic process for free expansion, select the '$WRONG$' statement out of the following options.

There is no change in internal energy of an ideal gas when it undergoes

What is a quasi-static process?

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 :