COMEDK 2025 Evening Shift | Thermodynamics Question 2 | Chemistry

In the decomposition of limestone to lime, the values of $\Delta H^o$ and $\Delta S^o$ are $+179.1 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and $160.2 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$. Calculate the temperature above which conversion of limestone to lime will be spontaneous, if values of $\Delta H^o$ and $\Delta S^o$ remain unchanged with temperature. [Assuming pressure 1 bar ]

1018 K

1200 K

1028 K

1118 K

COMEDK 2025 Evening Shift

MCQ (Single Correct Answer)

-0

The enthalpies of combustion of $\mathrm{H}_2, \mathrm{C}$ (graphite) and $\mathrm{C}_2 \mathrm{H}_6(\mathrm{~g})$ are $-286.0,-394.0$ and $-1560.0 \mathrm{~kJ} \mathrm{~mol}^{-1}$ at $25^{\circ} \mathrm{C}$ and 1 atm pressure. The enthalpy of formation of ethane is :

$-97.0 \mathrm{~kJ} \mathrm{~mol}^{-1}$

$-86.0 \mathrm{~kJ} \mathrm{~mol}^{-1}$

$-92.0 \mathrm{~kJ} \mathrm{~mol}^{-1}$

$-78.0 \mathrm{~kJ} \mathrm{~mol}^{-1}$

COMEDK 2025 Afternoon Shift

MCQ (Single Correct Answer)

-0

The Enthalpy of combustion of 1.0 mole of a reactive metal X at $27^{\circ} \mathrm{C}$ and 1.0 bar pressure to form a solid oxide ( XO ) is $-601.83 \mathrm{~kJ} / \mathrm{mol}$. The Internal energy change for this reaction is ___________ kJ. $$\left(\mathrm{R}=8.314 \mathrm{j} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\right)$$

701.33

754.58

$-$614.30

$-$600.58

COMEDK 2025 Afternoon Shift

MCQ (Single Correct Answer)

-0

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?

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

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

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

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

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