Which of the following is not a reversible change?

Options

A. Heating of water to steam
B. Cooking of eggs
C. Heating of wax to molten wax
D. None of these

Explanation

To determine which of the following is not a reversible change, we need to understand what reversible and irreversible changes are.

### Step-by-Step Solution:

1. **Understanding Reversible Changes**:
- A reversible change is one where the final substance can be transformed back into the original substance. For example, when water is heated and turns into steam, it can be cooled back into water.

2. **Analyzing the Options**:
- **Option A: Heating of water to steam**:
- This is a reversible change because steam can be cooled and converted back into water.
- **Option B: Cooking of eggs**:
- This is an irreversible change. Once eggs are cooked, they cannot be returned to their original raw state.
- **Option C: Heating of wax to molten wax**:
- This is a reversible change. When molten wax cools, it solidifies back into wax.
- **Option D: None of the above**:
- This option does not apply as we have identified an irreversible change.

3. **Conclusion**:
- The only option that represents a change that cannot be reversed is **Option B: Cooking of eggs**.

### Final Answer:
- The change that is not reversible is **Cooking of eggs (Option B)**.