1) Both carbon dioxide and water are pure substances. How are they similar to each other?

A. both substances have a set ratio of atoms that cannot be separated by physical means.

B. both substances have a set ratio of atoms that can be separated by physical means.

C. both substances have the same physical and chemical properties.

D. both substances have the same physical properties, but different chemical properties.

Its A

Pure substance is a set ratio of atoms that cannot be separated by physical means.

It's A

The correct answer is A. both substances have a set ratio of atoms that cannot be separated by physical means.

To understand why this is the correct answer, it helps to have some knowledge of the properties of pure substances like carbon dioxide and water.

Carbon dioxide (CO2) is composed of one carbon atom bonded to two oxygen atoms. The ratio of carbon to oxygen is always 1:2 in carbon dioxide, and this ratio cannot be changed by physical means such as heating or cooling.

Water (H2O) is composed of two hydrogen atoms bonded to one oxygen atom. The ratio of hydrogen to oxygen is always 2:1 in water, and similarly to carbon dioxide, this ratio cannot be altered by physical means.

So, both carbon dioxide and water have a fixed ratio of atoms that cannot be separated by physical means, making option A the correct answer.