Evidence of Chemical Reactions

Question 1

A piece of limestone erodes due to acid rain. This process can be best described as a

Revolt · Accepted Answer

slow chemical change.

Question 2

The images show two unrelated events occurring at separate times. Which event is most likely an example of a chemical reaction?

Revolt · Accepted Answer

Event 1 because there is a color change.

Question 3

When sodium metal is added to water, an orange flame is observed on the metal surface. Based on this observation, what can best be concluded?

Revolt · Accepted Answer

A chemical reaction occurs because heat and light are given off.

Question 4

During an experiment, a student observes the formation of a precipitate. Why does this indicate that a chemical reaction is likely occurring?

Revolt · Accepted Answer

A solid forms, and there is a change of color.

Question 5

Which statement describes a chemical reaction?

Revolt · Accepted Answer

Atoms in the reactants are rearranged to form new substances.

Question 6

Burning a piece of wood in fire can be best described as a

Revolt · Accepted Answer

chemical change because the atoms in wood and oxygen are rearranged.

Question 7

A solid is placed in a solution. Which observation most likely indicates that a chemical reaction has occurred?

Revolt · Accepted Answer

The solid has bubbles forming on its surface.

Question 8

The chemical formula below shows how salt is produced.HCl + NaOH NaCl + H2O Which substances are the reactants?

Revolt · Accepted Answer

HCl and NaOH

Question 9

The images show two processes. Image A: a roasting marshmallow Image B: melting iceWhich statement about the two images is true?

Revolt · Accepted Answer

Image A shows a chemical reaction, and image B shows a physical change.

Question 10

Which statement about a chemical reaction is true?

Revolt · Accepted Answer

It occurs whenever a chemical change takes place.

Evidence of Chemical Reactions Answers