For a sample of a perfect gas,when its pressure is changed isothermally from $p_i$ to $p_f$,the entropy change is given by:

Calculate the sign of $\Delta S$ for the melting of ice at $275 \ K$.

One mole of an ideal gas at $350 \, K$ is in a $2.0 \, L$ vessel with thermally conducting walls,which are in contact with the surroundings. It undergoes isothermal expansion from $2.0 \, L$ to $3.0 \, L$ against a constant external pressure of $4 \, atm$. The change in entropy of the surroundings $(\Delta S_{surr})$ is $...... \, J \, K^{-1}$ (Nearest integer). Given: $R = 8.314 \, J \, K^{-1} \, mol^{-1}$.

$9.0 \, g$ of $H_2O$ is vaporized at $100 \, ^\circ C$ and $1 \, atm$ pressure. If the latent heat of vaporization of water is $x \, J / g$,then $\Delta S$ is given by :-

What is meant by absolute entropy?

At $300 \ K$,for the reaction $A \rightarrow P$,the $\Delta S_{sys}$ is $5 \ J \ K^{-1} \ mol^{-1}$. What is the heat absorbed (in $kJ \ mol^{-1}$) by the system?