Question

Which of the following is not an example of a chemical reaction?

• A. Burning wood
• B. Rusting of an iron rod
• C. Photosynthesis in plants
• D. Melting ice

Answer 1

The correct option is D Melting ice

Any form of burning involves oxygen. When wood is burned, oxygen reacts with the elements in wood like carbon and others, and releases new substances like carbon dioxide. There are various new substances being created. So, this is a chemical change.

Rusting of an ironrod is a chemical reaction where iron reacts with oxygen and moisture, and turns to rust which is brownish red. The properties of rust are completely different from that of iron. Again, a chemical change.

Plants convert the carbon dioxide and water they take in from the surroundings to glucose and oxygen with the help of sunlight. Clearly, entirely new substances are being created. This is a chemical change.

However, when ice melts we just get water. The chemical composition is exactly the same, only the physical state is different. Ice is just solid water. There is no new substance formed. So this is not a chemical change.