Which of the following is not a chemical change ?

Options

A. Electrolysis of water
B. Boiling of water
C. Digestion of food
D. Burning of magnesium

Explanation

To determine which of the following options is not a chemical change, we need to understand what constitutes a chemical change. A chemical change occurs when substances react to form new products with different properties from the reactants. Let's analyze each option step by step:

1. **Electrolysis of Water**:
- In this process, water (H2O) is broken down into hydrogen gas (H2) and oxygen gas (O2) through the application of electrical energy.
- Since new substances are formed (H2 and O2) with different properties from water, this is a chemical change.

2. **Boiling of Water**:
- Boiling water involves heating it until it changes from a liquid state to a gaseous state (steam).
- The chemical composition of water remains the same (H2O), and no new substances are formed. Therefore, this is a physical change, not a chemical change.

3. **Digestion of Food**:
- During digestion, food is broken down by enzymes into simpler substances.
- This process results in the formation of new products, indicating a chemical change.

4. **Burning of Magnesium**:
- When magnesium is burned, it reacts with oxygen in the air to form magnesium oxide (MgO).
- This reaction produces a new substance, which is a clear indication of a chemical change.

Based on the analysis, the only option that does not represent a chemical change is:

**Answer: Boiling of Water (Option B)**