COMEDK 2025 Afternoon Shift | Thermodynamics Question 5 | Chemistry

For a hypothetical chemical reaction $\mathrm{A}_2+3 \mathrm{~B}_2+$ Heat $\cdots\rightarrow 2 \mathrm{AB}_3$, which one of the following combinations of state variables would support the spontaneity of the reaction at a particular temperature?

$\Delta \mathrm{H}<0, \Delta \mathrm{~S}>0, \Delta \mathrm{G}>0$

$\Delta \mathrm{H}>0, \Delta \mathrm{~S}>0, \Delta \mathrm{G}<0$

$\Delta \mathrm{H}>0, \Delta \mathrm{~S}<0, \Delta \mathrm{G}<0$

$\Delta \mathrm{H}>0, \Delta \mathrm{~S}<0, \Delta \mathrm{G}>0$

COMEDK 2025 Afternoon Shift

MCQ (Single Correct Answer)

-0

For the reaction $\mathrm{A}_2+\mathrm{B}_2 \cdots \cdots>2 \mathrm{AB}, \Delta \mathrm{H}_{\mathrm{f}}=-400 \mathrm{~kJ} / \mathrm{mol}$. The bond dissociation enthalpies of $\mathrm{A}_2$, $\mathrm{B}_2$ and AB are in the ratio $1: 0.75: 1$. What is the bond dissociation enthalpy of $\mathrm{B}_2$ in $\mathrm{kJ} / \mathrm{mol}$ ?

1600

2400

3200

800

COMEDK 2025 Morning Shift

MCQ (Single Correct Answer)

-0

0.4 g of Propane burns completely at 300 K in a bomb calorimeter. The temperature of the calorimeter and surrounding water rises by $0.4^0 \mathrm{C}$. If the heat capacity of the calorimeter and contents is $24 \mathrm{~kJ} \mathrm{~K}^{-1}$ what is the Enthalpy for the reaction? (Assume that propane gas shows ideal behaviour).

$-$1006.9 kJ

$-$1063.5 kJ

$-$2084.6 kJ

$-$1902.8 kJ

COMEDK 2025 Morning Shift

MCQ (Single Correct Answer)

-0

For a reaction $\mathrm{X}_2(\mathrm{l})+\mathrm{Y}_2(\mathrm{~g}) \leftrightharpoons 2 \mathrm{XY}(\mathrm{g})$, the $\Delta \mathrm{H}^0$ and $\Delta \mathrm{S}^0$ are $+29.3 \mathrm{~kJ} / \mathrm{mol}$ and $104.1 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$ respectively at 298 K . Find the free energy change in $\mathrm{kJ} / \mathrm{mol}$.

0.6

2.04

5.2

1.72

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