Change in entropy for an ideal gas in a reversible isothermal process is given by:

$1.8 \ g$ of water is vaporized by supplying $4 \ kJ$ of heat at $100^{\circ}C$. What is the molar heat of vaporization of water at the same temperature?

The entropy change associated with the conversion of $1 \ kg$ of ice at $273 \ K$ to water vapours at $383 \ K$ is: (Specific heat of water liquid and water vapours are $4.2 \ kJ \ K^{-1} \ kg^{-1}$ and $2.0 \ kJ \ K^{-1} \ kg^{-1},$ heat of fusion and vaporisation of water are $334 \ kJ \ kg^{-1}$ and $2491 \ kJ \ kg^{-1},$ respectively) $(\ln \ 273 = 5.61, \ln \ 373 = 5.92, \ln \ 383 = 5.95)$

$1 \, mol$ of oxygen gas is heated at constant volume from $20 \, ^oC$ to $30 \, ^oC$. What will be the change in the internal energy of the gas? Given the molar heat capacity of oxygen at constant pressure,$C_P = 7.03 \, cal \, mol^{-1} \, K^{-1}$ and $R = 2 \, cal \, mol^{-1} \, K^{-1}$. (Answer in $cal$)

Enthalpy of neutralisation of acetic acid by $NaOH$ is $-50.6 \ kJ/mol$ and the heat of neutralisation of a strong acid with a strong base is $-55.9 \ kJ/mol$. What is the value of $\Delta H$ for the ionisation of $CH_3COOH$ in $kJ/mol$?

One mole of an ideal gas is allowed to expand freely and adiabatically into vacuum until its volume has doubled. Which of the following statements is $NOT$ true concerning this expansion?