General Principles and Processes of Isolation of Metals — JEE Main · 2023 · 01 Feb 2023 · Shift 1 Question with Solution

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: In an Ellingham diagram, the oxidation of carbon to carbon monoxide shows a negative slope with respect to temperature.
Reason R: CO tends to get decomposed at higher temperature.
In the light of the above statements, choose the correct answer from the options given below

(A)Both $A$ and $R$ are correct and $R$ is the correct explanation of $A$
(B) $A$ is not correct but $R$ is correct
(C)Both $A$ and $R$ are correct but $R$ is NOT the correct explanation of $A$
(D) $A$ is correct but $R$ is not correct✓ Correct

Answer: (D)

Solution

For the oxidation

2 C + O_{2} \to 2 CO

the number of gaseous moles rises from one to two, so the entropy change is positive. In an Ellingham diagram the plotted quantity is

Δ G^{\circ} = Δ H^{\circ} - T Δ S^{\circ}

, whose slope against temperature is

- Δ S^{\circ}

; a positive

Δ S^{\circ}

gives a negative slope, so this line alone falls as temperature increases and the assertion is correct. Carbon monoxide does not decompose on heating; on the contrary it grows more stable and a stronger reducing agent at high temperature, which is exactly why its formation line descends. The assertion is correct but the reason is not.

JEE Main · 2023 · 01 Feb 2023 · Shift 1 · Single correct option

JEE Main · 2023 · 01 Feb 2023 · Shift 1 · General Principles and Processes of Isolation of Metals

Solution

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