$A$ $10 \ g$ piece of iron $(C = 0.45 \ J/g \ ^oC)$ at $100 \ ^oC$ is dropped into $25 \ g$ of water $(C = 4.2 \ J/g \ ^oC)$ at $27 \ ^oC$. Find the temperature of the iron and water system at thermal equilibrium in $^oC$.

Consider the following data for the reaction $X_2(g) + Y_2(g) \rightleftharpoons 2XY(g)$ at $600 \ K$. The $\Delta_r G^\circ$ (in $kJ \ mol^{-1}$) for the reaction is:

Compound	$\Delta_f H^\circ$ $(kJ \ mol^{-1})$	$S^\circ$ $(J \ mol^{-1} \ K^{-1})$
$XY(g)$	$42$	$200$
$X_2(g)$	$8$	$140$
$Y_2(g)$	$80$	$250$

The heat of vaporisation and heat of fusion of $H_2O$ are $540 \, cal/g$ and $80 \, cal/g$. The ratio of $\frac{\Delta S_{vap}}{\Delta S_{fusion}}$ for water is :-

If $\Delta G$ and $\Delta S$ for the reaction $A_{(g)} \rightarrow B_{(g)} + 2C_{(g)}$ at $2000 \ K$ are $-40 \ kJ \ mol^{-1}$ and $0.22 \ kJ \ K^{-1} \ mol^{-1}$ respectively,the change in internal energy for the same reaction approximately (in $kJ \ mol^{-1}$) is

The reaction of cyanamide,$NH_2CN_{(s)}$,with dioxygen was carried out in a bomb calorimeter,and $\Delta U$ was found to be $-742.7 \ kJ \ mol^{-1}$ at $298 \ K$. Calculate the enthalpy change for the reaction at $298 \ K$.
$NH_2CN_{(s)} + \frac{3}{2}O_{2_{(g)}} \to N_{2_{(g)}} + CO_{2_{(g)}} + H_2O_{(l)}$

In a constant pressure process for $5 \text{ mole}$ of an ideal monoatomic gas,the temperature of the gas increased from $300 \ K$ to $500 \ K$. Which of the following is incorrect regarding the process?