Question

7a. what event is occurring? liquid a 25°c liquid b 25°c 60°c 7b. circle chemical change or physical change 8a. what event is occurring? 8b. circle chemical change or physical change

Explanation:

Step1: Recall definitions

A chemical change results in new substances with different chemical properties, while a physical change only alters physical properties like state, shape, or size without forming new substances.

Step2: Analyze 7a

When two liquids are mixed and there is a temperature - change and possibly a gas is evolved, new substances are likely formed. This indicates a chemical change.

Step3: Analyze 8a

Heating a substance and observing a change in its state (e.g., melting or boiling) is a physical change as no new substances are formed. It is just a change in the physical state of the matter.

Answer:

7a: Chemical change
8a: Physical change