Which of the following is not correct observation on Ellingham diagram ?

Options

A. A metal can reduce the oxide of other metal which lies below it in Ellingham diagram .
B. CO is more effective than C as a reducing agent below `710^(@)C`
C. `DeltaG^(@)` of metal oxides is higher than that of `CO_(2)` hence oxidation of metal suphides to oxides is not favourable.
D. Need for conversion of metal sulphide to metal oxide before reduction can be explained thermodynamically.

Explanation

To solve the question regarding which observation on the Ellingham diagram is not correct, we will analyze the provided statements step by step.

### Step-by-Step Solution:

1. **Understanding the Ellingham Diagram**:
The Ellingham diagram is a graphical representation that shows the stability of metal oxides as a function of temperature. The y-axis represents the Gibbs free energy change (ΔG) for the formation of oxides, while the x-axis represents temperature.

2. **Analyzing Statement 1**:
The first statement claims that "a metal can reduce the oxides of other metals which lie below in the Ellingham diagram."
- **Explanation**: In the Ellingham diagram, a metal can only reduce the oxides of metals that are positioned above it in the diagram. This is because the more negative the ΔG, the more stable the oxide. Therefore, a metal cannot reduce an oxide that is more stable (i.e., has a more negative ΔG) than its own oxide.
- **Conclusion**: This statement is incorrect.

3. **Analyzing Statement 2**:
The second statement states that "CO is a more effective reducing agent than carbon below 710 degrees Celsius."
- **Explanation**: This statement is generally correct. Below this temperature, CO is indeed a better reducing agent than carbon because it can reduce metal oxides more effectively due to its favorable Gibbs free energy change compared to carbon.
- **Conclusion**: This statement is correct.

4. **Analyzing Statement 3**:
The third statement mentions that "the ΔG for metal oxide is higher than that of CO2, hence oxidation of metal sulfide to oxide is not favorable."
- **Explanation**: This statement is also correct. If the ΔG for the formation of metal oxides is higher than that for CO2, it indicates that the oxidation of metal sulfides to oxides is thermodynamically unfavorable.
- **Conclusion**: This statement is correct.

5. **Analyzing Statement 4**:
The fourth statement discusses the need for the conversion of metal sulfide to metal oxide before reduction can be explained thermodynamically.
- **Explanation**: This statement is correct as well. Before a metal sulfide can be reduced, it typically must first be converted to a metal oxide, which is a more stable form.
- **Conclusion**: This statement is correct.

### Final Conclusion:
Based on the analysis, the only incorrect observation regarding the Ellingham diagram is Statement 1. Therefore, the answer to the question is:

**Answer: A (The statement that a metal can reduce the oxides of other metals which lie below in the Ellingham diagram is incorrect.)**