For the vaporization of water at $1 \, \text{atm}$ pressure,the liquid water and water vapor are in equilibrium. What is the temperature in $K$?
$H_2O_{(l)} \rightleftharpoons H_2O_{(g)}$ [at $1 \, \text{atm}$ pressure] [$\Delta S = 120 \, J K^{-1}$ and $\Delta H = +45.0 \, kJ$]

The total entropy change for a system and its surroundings increases,if the process is

Entropy is maximum in case of

Which of the following processes is non-spontaneous?

For the reaction: $H^{+}_{(aq)} + OH^{-}_{(aq)} \rightarrow H_{2}O_{(l)}$,given the standard molar entropies $S^{o}(298 \ K)$ in $J \ K^{-1} \ mol^{-1}$ as $S^{o}(H^{+}) = 0$,$S^{o}(OH^{-}) = -10.7$,and $S^{o}(H_{2}O) = 70$. The standard entropy change $\Delta S^{o}$ for the reaction is ..... $J \ K^{-1} \ mol^{-1}$.

What is entropy? Explain its role in spontaneity.