The heats of combustion $\Delta H$ of $CH_4$,$C_2H_6$,$C_2H_4$,and $C_2H_2$ gases are $-212.8$,$-373.0$,$-337.0$,and $-310.5 \ kcal$ respectively at the same temperature. Which of these gases is the best fuel?

The process of evaporation of a liquid is completed by .......

Which one of the following is always not negative?

One mole of $CH_3OH$ is vaporized at $338 \ K$ and $1.5 \ atm$ pressure. If the enthalpy of vaporization of $CH_3OH$ is $35.57 \ kJ/mol$,calculate the value of $\Delta U$ for the process in $kJ$. (in $.76$)

$CsOH + HCl \to CsCl + H_2O$,$\Delta H = -13.4 \ K \ cal/mol$
$CsOH + HA \to CsA + H_2O$,$\Delta H = -10.4 \ K \ cal/mol$
Then calculate $\Delta H$ of ionisation of $HA$ in $K \ cal/mol$.

One gram sample of $NH_4NO_3$ is decomposed in a bomb calorimeter. The temperature of the calorimeter increases by $6.12 \ K$. The heat capacity of the system is $1.23 \ kJ/K$. What is the molar heat of decomposition for $NH_4NO_3$ in $kJ/mol$?