COMEDK 2026 Afternoon Shift | Thermodynamics Question 1 | Chemistry

The standard enthalpies of formation of $\mathrm{CH}_4(\mathrm{~g}), \mathrm{CO}_2(\mathrm{~g})$ and $\mathrm{H}_2 \mathrm{O}(\mathrm{l})$ are $-74.8 \mathrm{~kJ} \mathrm{~mol}^{-1},-393.5 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and $-285.8 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively. Then the enthalpy change for the given reaction in $\mathrm{kJ} \mathrm{mol}^{-1}$ will be:

$$ 2 \mathrm{CH}_4(\mathrm{~g})+4 \mathrm{O}_2(\mathrm{~g}) \rightarrow 2 \mathrm{CO}_2(\mathrm{~g})+4 \mathrm{H}_2 \mathrm{O}(\mathrm{l}) $$

$ -890.3$

$+890.3$

$+1780.6$

$ -1780.6$

COMEDK 2026 Afternoon Shift

MCQ (Single Correct Answer)

-0

Identify the INCORRECT statement

For spontaneous process $\left(\left[\Delta H_{\text {system }}-T \Delta S_{\text {system }}\right]\right)<0$

Entropy is an extensive property and state function

A process will always be spontaneous at all temperatures, if $\mathrm{T} \Delta \mathrm{S}$ is positive

At 273 K , for the transition Ice $(s) \longrightarrow$ Water $(l), \Delta \mathrm{G}=0$

COMEDK 2026 Morning Shift

MCQ (Single Correct Answer)

-0

Ozone is formed by the reaction

$$ \mathrm{O}_{2(g)}+\mathrm{O}_{(g)} \rightarrow \mathrm{O}_{3(g)}, \Delta \mathrm{H}=-107.2 \mathrm{~kJ} . $$

Given $\mathrm{O}=0$ bond energy is $498.0 \mathrm{~kJ} \mathrm{~mol}^{-1}$, the average bond energy of ozone is:

$302.6 \mathrm{~kJ} \mathrm{~mol}^{-1}$

$520.6 \mathrm{~kJ} \mathrm{~mol}^{-1}$

$120.5 \mathrm{~kJ} \mathrm{~mol}^{-1}$

$201.8 \mathrm{~kJ} \mathrm{~mol}^{-1}$

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