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

Options

A. A is correct but R is not correct
B. A is not correct but `R` is not correct
C. Both `A` and `R` are correct and `R` is the correct explanation of `A`
D. Both `A` and `R` are correct but `R` is NOT the correct explanation of `A`

Answer

To solve the question, we need to analyze both the Assertion (A) and the Reason (R) provided.

### Step 1: Analyze the Assertion (A)
**Assertion A:** "In an Ellingham diagram, the oxidation of carbon to carbon monoxide shows a negative slope with respect to temperature."

- The Ellingham diagram is a graphical representation that shows the temperature dependence of the stability of compounds.
- The oxidation of carbon to carbon monoxide can be represented by the reaction:
\[ C + \frac{1}{2} O_2 \rightarrow CO \]
- The Gibbs free energy change (\( \Delta G \)) for this reaction is affected by temperature. According to the Gibbs free energy equation:
\[ \Delta G = \Delta H - T \Delta S \]
- For the reaction of carbon to carbon monoxide, the entropy change (\( \Delta S \)) is positive because a solid (C) is converted to a gas (CO).
- Therefore, as the temperature increases, the term \( T \Delta S \) becomes more significant, leading to a decrease in \( \Delta G \), which indicates that the reaction becomes more favorable at higher temperatures.
- This results in a negative slope in the Ellingham diagram for this reaction.

### Conclusion for Assertion:
- The assertion is **correct** because the oxidation of carbon to carbon monoxide does indeed show a negative slope with respect to temperature in the Ellingham diagram.

### Step 2: Analyze the Reason (R)
**Reason R:** "CO tends to get decomposed at higher temperature."

- Carbon monoxide (CO) can decompose into carbon (C) and oxygen (O) at high temperatures:
\[ 2CO \rightarrow C + O_2 \]
- The decomposition of CO is an endothermic process, which means that at higher temperatures, the equilibrium can shift towards the formation of reactants (C and O2).
- This indicates that CO is less stable at high temperatures, which aligns with the concept that the stability of compounds can change with temperature.

### Conclusion for Reason:
- The reason is also **correct** because CO does tend to decompose at higher temperatures.

### Final Conclusion:
- Both the assertion and reason are correct, but the reason does not explain the assertion directly. Therefore, the correct answer is that both statements are true, but the reason is not the correct explanation for the assertion.

### Answer:
- The correct answer is: **Both A and R are true, but R is not the correct explanation of A.**

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