JEE Main 2023 — Chemistry Physical Chemistry

2023mcqmedium

Given

(A) $2\mathrm{CO}(g)+{O}_{2}(g)\rightarrow 2{\mathrm{CO}}_{2}(g){\Delta H}_{1}^{o}=-x\mathrm{kJ}{\mathrm{mol}}^{-1}$

(B) $C(\mathrm{graphite})+{O}_{2}(g)\rightarrow {\mathrm{CO}}_{2}(g){\Delta H}_{2}^{o}=-y\mathrm{kJ}{\mathrm{mol}}^{-1}$

The $\Delta {H}^{o}$ for the reaction $C(\mathrm{graphite})+\frac{1}{2}{O}_{2}(g)\rightarrow \mathrm{CO}(g)$ is

Official previous-year question

Held on 10 Apr 2023 · Verified 6 Jul 2026.

Options

A
$\frac{2x-y}{2}$
B
$\frac{x+2y}{2}$
C
$\frac{x-2y}{2}$
D
$2y-x$

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Solution

(A) $2\mathrm{CO}(g)+{O}_{2}(g)\rightarrow 2{\mathrm{CO}}_{2}(g){\Delta H}_{1}^{o}=-x\mathrm{kJ}{\mathrm{mol}}^{-1}$

(B) ${C}_{\mathrm{graphite}}+{O}_{2}(g)\rightarrow {\mathrm{CO}}_{2}(g){\Delta H}_{2}^{o}=-y\mathrm{kJ}{\mathrm{mol}}^{-1}$

If the equation is multiplied the value $n$ , then the enthalpy change value also multiplied by factor $n.$ If the enthalpy is positive in one direction, it is negative in other direction.

Multiply equation $B$ by $2$ and subtract equation $(A)$ from it

$2{C}_{\mathrm{graphite}}+{O}_{2}(g)\rightarrow 2\mathrm{CO}(g){\Delta H}^{\circ }=x-2y$

${C}_{\mathrm{graphite}}+\frac{1}{2}{O}_{2}\rightarrow \mathrm{CO};{\Delta H}^{\circ }=\frac{x-2y}{2}$

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Solution

(A) $2\mathrm{CO}(g)+{O}_{2}(g)\rightarrow 2{\mathrm{CO}}_{2}(g){\Delta H}_{1}^{o}=-x\mathrm{kJ}{\mathrm{mol}}^{-1}$

(B) ${C}_{\mathrm{graphite}}+{O}_{2}(g)\rightarrow {\mathrm{CO}}_{2}(g){\Delta H}_{2}^{o}=-y\mathrm{kJ}{\mathrm{mol}}^{-1}$

If the equation is multiplied the value $n$ , then the enthalpy change value also multiplied by factor $n.$ If the enthalpy is positive in one direction, it is negative in other direction.

Multiply equation $B$ by $2$ and subtract equation $(A)$ from it

$2{C}_{\mathrm{graphite}}+{O}_{2}(g)\rightarrow 2\mathrm{CO}(g){\Delta H}^{\circ }=x-2y$

${C}_{\mathrm{graphite}}+\frac{1}{2}{O}_{2}\rightarrow \mathrm{CO};{\Delta H}^{\circ }=\frac{x-2y}{2}$

JEE Main 2023 — Chemistry Physical Chemistry

Options

Did you get this right?

Solution

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JEE Main Physical Chemistry in other years

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JEE Main 2023 — Chemistry Physical Chemistry

Options

Did you get this right?

Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

Keep practicing Physical Chemistry