Observe the following reactions:
$AB_{(g)} + 25 H_2O_{(l)} \rightarrow AB_{(25 H_2O)} ; \Delta H = x \ kJ \ mol^{-1}$
$AB_{(g)} + 50 H_2O_{(l)} \rightarrow AB_{(50 H_2O)} ; \Delta H = y \ kJ \ mol^{-1}$
The enthalpy of dilution $(\Delta H_{dil})$ in $kJ \ mol^{-1}$ is

The $\Delta E^o$ of combustion of $2-$methylpropene is $-X \ kJ \ mol^{-1}$. The value of $\Delta H^o$ is

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,
$(A) \ q = 0$
$(B) \ T_2 = T_1$
$(C) \ P_2 V_2 = P_1 V_1$
$(D) \ P_2 V_2^\gamma = P_1 V_1^\gamma$

An ideal gas is allowed to expand both reversibly and irreversibly in an isolated system. If $T_i$ is the initial temperature and $T_f$ is the final temperature,which of the following statements is correct?

For the reaction at $25^{\circ} C$,$X_2O_{4(l)} \longrightarrow 2 XO_{2(g)}$,$\Delta U$ and $\Delta S$ are $2.1 \ kCal$ and $20 \ cal \ K^{-1}$ respectively. What is $\Delta G$ for the reaction at the same temperature? $(R = 2 \ cal \ K^{-1} \ mol^{-1})$

The heats of combustion of $C_2H_4, C_2H_6$ and $H_2$ are $-1409.5 \, kJ, -1558.3 \, kJ$ and $-285.6 \, kJ$ respectively. The heat of hydrogenation of ethene is ...... $kJ$.