At $25^{\circ} C$,$50 \ g$ of iron reacts with $HCl$ to form $FeCl_2$. The evolved hydrogen gas expands against a constant pressure of $1 \ bar$. The work done by the gas during this expansion is ....... $J$. (Round off to the Nearest Integer) [Given : $R = 8.314 \ J \ mol^{-1} \ K^{-1}$. Assume,hydrogen is an ideal gas] [Atomic mass of $Fe$ is $55.85 \ u$]

An ideal gas in a thermally insulated vessel at internal pressure $= P_1$,volume $= V_1$ and absolute temperature $= T_1$ expands irreversibly against zero external pressure,as shown in the diagram. The final internal pressure,volume and absolute temperature of the gas are $P_2, V_2$ and $T_2$,respectively. For this expansion,
$(A) \ q = 0$
$(B) \ T_2 = T_1$
$(C) \ P_2 V_2 = P_1 V_1$
$(D) \ P_2 V_2^\gamma = P_1 V_1^\gamma$

Which one of the following is always not negative?

The enthalpy of combustion of methane at $25\,^{\circ}C$ is $890\,kJ$. The heat liberated when $3.2\,g$ of methane is burnt in air is.....$kJ$

Which of the following statements or relationships is not correct in thermodynamic changes?

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) $(\ln \ 273 = 5.61, \ln \ 373 = 5.92, \ln \ 383 = 5.95)$