Question

pure sodium metal placed in water will spark and ignite, as well as form bubbles and gas. what are the signs that this is a chemical reaction? check all that apply.
heat is produced.
light is produced.
heat is absorbed.
bubbles appear.
a precipitate forms.
the color changes.

Explanation:

When sodium reacts with water, it is an exothermic reaction which produces heat and light (spark and ignite). Bubbles appear due to the formation of gas. There is no mention of heat absorption, precipitate formation or color - change in the given description.

Answer:

Heat is produced.
Light is produced.
Bubbles appear.