In isothermal expansion,the pressure is determined by

$Assertion :$ The isothermal curves intersect each other at a certain point.
$Reason :$ The isothermal change takes place slowly,so,the isothermal curves have very little slope.

An ideal gas is trapped inside a test tube of cross-sectional area $20 \times 10^{-6} \, m^2$ as shown in the figure. The gas occupies a height $L_1$ at the bottom of the tube and is separated from air at atmospheric pressure by a mercury column of mass $0.002 \, kg$. If the tube is quickly turned isothermally,upside down,the gas now occupies height $L_2$ in the tube. Find the ratio $L_2/L_1$. [Take atmospheric pressure $P_0 = 10^5 \, Nm^{-2}$ and $g = 10 \, ms^{-2}$]

When heat is given to a gas in an isothermal change,the result will be

The internal energy of an ideal gas increases during an isothermal process when the gas is

One mole of an ideal monoatomic gas is compressed isothermally in a rigid vessel to double its pressure at room temperature,$27\,^{\circ}C$. The work done on the gas will be