Question

grade 7 science: unit 1 – pre- assessment how can i make new things from old things? student clayton sneed class 703 date 1. which of the following is an example of a chemical reaction? a. mixing lemonade powder with water b. burning marshmallows over a fire c. melting butter in a pan d. boiling water on a stove 2. a chemical reaction...

Explanation:

To determine a chemical reaction, we check for new substance formation.

• Option A: Mixing lemonade powder with water is dissolving (physical change, no new substance).
• Option B: Burning marshmallows involves combustion, forming new substances (like ash, gases) – a chemical reaction.
• Option C: Melting butter is a phase change (physical, no new substance).
• Option D: Boiling water is a phase change (physical, no new substance).

Answer:

B. burning marshmallows over a fire