$A$ monatomic gas of volume $V$ and pressure $P$ expands isothermally to a volume $27 V$ and then is compressed adiabatically to a volume $V$. The final pressure of the gas is: (in $P$)

$1$ mole of rigid diatomic gas performs a work of $Q/5$ when heat $Q$ is supplied to it. The molar heat capacity of the gas during this transformation is $\frac{xR}{8}.$ The value of $x$ is $\ldots \ldots \ldots .$ $[R =$ universal gas constant $]$

Which of the following statements is correct?

In thermodynamics,heat and work are

$1\,g$ of a liquid is converted to vapour at $3 \times 10^5\,Pa$ pressure. If $10\%$ of the heat supplied is used for increasing the volume by $1600\,cm^3$ during this phase change,then the increase in internal energy in the process will be $............\,J$.

The change in internal energy of a given mass of a gas,when its volume changes from $V$ to $3V$ at constant pressure $P$,is (where $\gamma$ is the ratio of the specific heat capacities of the gas).