Question

1. an uneffected change in ___ is a sign that chemical reactions may have occured.

word bank: temperature, light, odor, evidence, molecules, color, precipitate, gas.

Explanation:

In a chemical reaction, an unexpected change in temperature is a common sign. For example, in exothermic reactions, heat is released (temperature increase), and in endothermic reactions, heat is absorbed (temperature decrease). Other options like light, odor, color, precipitate, and gas are also signs but temperature change is a very typical and fundamental one among them.

Answer:

temperature