Question

Which of the below-given process represents a physical change?

• A. Rusting of iron
• B. Combustion of magnesium ribbon
• C. Burning of a candle
• D. Melting of wax

Answer 1

The correct option is D

Melting of wax

Step 1: Explanation of the correct option

In the case of option D,

1. A physical change occurs when only the physical properties of a substance change.
2. Physical changes are reversible in nature. There is no new substance generated when the candle melts, and the molten wax may be solidified and converted into a candle again, making it a reversible transformation. Therefore, the melting of wax is a physical change.

Step 2: Explanation for the incorrect options

In the case of option A,

1. A chemical change is defined as a change in which one or more new compounds are produced.
2. The formation of rust occurs when the iron is exposed to air and moisture.
3. During rusting a new substance called iron oxide is formed. The color of the iron's surface also changes. As a result, rusting is a chemical change.

In the case of option B,

1. When magnesium ribbon is burned, a new substance known as magnesium oxide is produced.
2. Since the properties of magnesium oxide is totally different from magnesium ribbon so this is considered a chemical change

In the case of option C,

1. The burning of a candle is a chemical change because this change is permanent in nature.
2. Once the candle is burned, a completely new product is formed with a different composition than a candle.

Hence, option D is the correct answer.