Shyam was cooking potato curry on a chulha. To his surprise he observed that the copper vessel was getting blackened from outside. It may be due to:

Options

A. proper combustion of fuel.
B. improper cooking of potato curry.
C. improper combustion of the fuel.
D. burning of copper vessel.

Answer

**Step-by-Step Solution:**

1. **Understanding the Situation**: Shyam is cooking potato curry on a chulha (a traditional stove) and notices that the copper vessel is getting blackened from the outside.

2. **Identifying the Cause**: The blackening of the copper vessel suggests that there is some form of incomplete combustion occurring.

3. **Analyzing Combustion**: Combustion is a chemical process where a substance reacts with oxygen to produce heat and light. Proper combustion occurs when there is enough oxygen available, resulting in a clean burn without any soot or black residue.

4. **Considering Options**:
- **Option 1: Proper combustion of heat** - This would not cause blackening; instead, the vessel would remain clean.
- **Option 2: Improved cooking for potato curry** - This is irrelevant to the blackening of the vessel.
- **Option 3: Improper combustion of fuel** - This is likely the cause of the blackening. When there is insufficient oxygen, incomplete combustion occurs, leading to the formation of soot, which blackens the vessel.
- **Option 4: Burning of the copper vessel** - Copper does not burn in the way organic materials do; thus, this option is incorrect.

5. **Conclusion**: The most plausible explanation for the blackening of the copper vessel is due to improper combustion of the fuel, which leads to the formation of soot.

6. **Final Answer**: The correct answer is that the blackening of the copper vessel is due to improper combustion of the fuel.

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