Question

which of the following is an example of a chemical change? a mixing two substances and seeing bubbles b dissolving powder into water c coloring on paper to produce a color change d cutting wood to change the shape

Explanation:

To determine a chemical change, we look for the formation of new substances (indicated by signs like gas production, precipitate, color change due to reaction, etc.).

• Option A: Mixing two substances and seeing bubbles (gas production) suggests a chemical reaction (new substance, like a gas, is formed).
• Option B: Dissolving powder in water is a physical change (no new substance, just a solution).
• Option C: Coloring paper is a physical change (the color is from the dye, no new substance formed via reaction).
• Option D: Cutting wood is a physical change (only shape changes, no new substance).

So, A involves a chemical change as gas (a new substance) is produced.

Answer:

A. Mixing two substances and seeing bubbles