If a refrigerator's door is opened in a closed room,then we get:

For which of the following thermodynamic processes is $\Delta U = 0$?

$X \, g$ of ice at $0^{\circ} C$ is added to $340 \, g$ of water at $20^{\circ} C$. The final temperature of the resultant mixture is $5^{\circ} C$. The value of $X$ (in $g$) is closest to:
[Heat of fusion of ice $= 333 \, J / g$; specific heat of water $= 4.184 \, J / g \cdot K$]

The standard molar enthalpies of formation for ethane,$CO_2$,and water $(l)$ are $-21.1$,$-94.1$,and $-68.3 \text{ kcal/mol}$ respectively. What is the standard molar enthalpy of combustion for ethane in $\text{kcal/mol}$?

Match the transformations in column $I$ with appropriate options in column $II$.

Column $I$	Column $II$
$A$. $CO_{2(s)} \rightarrow CO_{2(g)}$	$p$. phase transition
$B$. $CaCO_{3(s)} \rightarrow CaO_{(s)} + CO_{2(g)}$	$q$. allotropic change
$C$. $2H_{(g)} \rightarrow H_{2(g)}$	$r$. $\Delta H$ is positive
$D$. $P_{(\text{white, solid})} \rightarrow P_{(\text{red, solid})}$	$s$. $\Delta S$ is positive
	$t$. $\Delta S$ is negative

$0.3 \ g$ of ethane undergoes combustion at $27^{\circ} C$ in a bomb calorimeter. The temperature of the calorimeter system (including the water) is found to rise by $0.5^{\circ} C$. The heat evolved during combustion of ethane at constant pressure is $....... kJ \ mol^{-1}$. (Nearest integer) [Given: The heat capacity of the calorimeter system is $20 \ kJ \ K^{-1}$,$R = 8.3 \ J \ K^{-1} \ mol^{-1}$. Assume ideal gas behaviour. Atomic mass of $C$ and $H$ are $12$ and $1 \ g \ mol^{-1}$ respectively]