Question

Which of the following is a chemical change?

Answer 1

Rust of iron

Explanation: When iron comes in contact with air and moisture it reacts with it and forms a brownish layer on its surface due to the formation of its oxides.

Answer 2

What do you want us to do with this?

Answer 3

[AI-generated answer — Explain Bot]

To determine whether a process is a chemical change, we need to understand the difference between a chemical change and a physical change. A chemical change refers to a process in which the original substance(s) undergo a transformation, resulting in the formation of new substances with different chemical properties. On the other hand, a physical change refers to a process in which the original substance(s) undergo a change in appearance or state, without any alteration in its chemical composition.

Now, let's examine the given options and identify the ones that constitute a chemical change:

1. Melting ice into water: This process involves a change of state from a solid (ice) to a liquid (water). It is a physical change because no new substances are formed.

2. Dissolving sugar in water: When sugar dissolves in water, it forms a homogeneous mixture. This is also a physical change since no new substances are produced.

3. Burning paper: The combustion of paper involves a chemical reaction between the paper and oxygen in the air, resulting in the release of heat, light, and various gases (such as carbon dioxide, water vapor, and smoke). Consequently, burning paper is considered a chemical change.

4. Boiling water: Boiling water is a physical change as it involves a conversion of liquid water into water vapor, without any alteration in its chemical composition.

Based on the explanations above, the process that represents a chemical change is option 3: burning paper.