For which of the following activities might you want to hire a chemist?

A. examining the structure of plant cells

B. building a fence

C. building a wood storage shed

D. testing a rock sample for gold content

Which of the following procedures involves a physical change in one of the substances?

A. creating salt by reacting sodium metal and chlorine gas

B. allowing a nail rust

C. separating a salt solution by evaporating the water

D. building a model rocket propelled by mixing baking soda and vinegar

For which of the following activities might you want to hire a chemist?

Answer: D. testing a rock sample for gold content

Which of the following procedures involves a physical change in one of the substances?

Answer: C. separating a salt solution by evaporating the water

A. examining the structure of plant cells

Incorrect. A biologist is required.

B. building a fence

Incorrect. A carpenter is required.

C. building a wood storage shed

Incorrect. A carpenter is required.

D. testing a rock sample for gold content

Incorrect. A chemist is required.

A. creating salt by reacting sodium metal and chlorine gas

Incorrect. This is a chemical change as a new product is formed.

B. allowing a nail rust

Incorrect. This is a chemical change as it is the oxidation of iron to form iron oxide, rust.

C. separating a salt solution by evaporating the water

Correct. This is a physical change as salt gets separated from water and no new product is formed.

D. building a model rocket propelled by mixing baking soda and vinegar

Incorrect. This is a chemical change.