For a dimerization reaction,$2 A_{(g)} \rightarrow A_{2(g)}$ at $298 \ K$,$\Delta U^{\ominus} = -20 \ kJ \ mol^{-1}$,$\Delta S^{\ominus} = -30 \ J \ K^{-1} \ mol^{-1}$,then the $\Delta G^{\ominus}$ will be........ $J$

$9.0 \ g$ of $H_2O$ is vaporised at $100 \ ^oC$ and $1 \ atm$ pressure. If the latent heat of vaporisation of water is $x \ J/g$,then $\Delta S$ is given by

Which of the following is incorrect?

The enthalpies of formation of gaseous $N_2O$ and $NO$ at $298 \ K$ are $82.0$ and $90.0 \ kJ \ mol^{-1}$ respectively. The enthalpy change of the reaction $N_2O_{(g)} + \frac{1}{2} O_{2(g)} \rightarrow 2 NO_{(g)}$ is

For an ideal gas, consider only $P-V$ work in going from an initial state $X$ to the final state $Z$. The final state $Z$ can be reached by either of the two paths shown in the figure. Which of the following choice(s) is (are) correct? [take $\Delta S$ as change in entropy and $w$ as work done].
(A) $\Delta S_{X \to Z} = \Delta S_{X \to Y} + \Delta S_{Y \to Z}$
(B) $w_{X \to Z} = w_{X \to Y} + w_{Y \to Z}$
(C) $w_{X \to Y \to Z} = w_{X \to Y} + w_{Y \to Z}$
(D) $\Delta S_{X \to Y \to Z} = \Delta S_{X \to Y}$

$A$ steel steam boiler has a mass of $900 \, kg$ and contains $400 \, kg$ of water. If the boiler and water receive only $70 \%$ of the heat supplied,how much heat in $kcal$ is required to raise the temperature of the boiler and water from $10 \, ^oC$ to $100 \, ^oC$? (Specific heat of steel = $0.11 \, kcal/kg \cdot K$,Specific heat of water = $1.0 \, kcal/kg \cdot K$)