Question

a scientist is conducting an investigation that involves water, silver, carbon dioxide, and oxygen gas. which group of statements best describe all of the materials he is using in the investigation?
○ they are each compounds. each of the compounds is made of atoms. all of the atoms are made of matter.
○ they are each made of matter. some are compounds and some are elements. they all contain atoms.
○ they are all elements. some contain molecules of the same type of atom. some contain different types of atoms.
○ they are each made of matter. some are compounds made of one type of element. some are pure atoms.

Explanation:

1. Analyze each substance:

• Water ($H_2O$) is a compound (made of hydrogen and oxygen atoms).
• Silver (Ag) is an element (made of silver atoms).
• Carbon dioxide ($CO_2$) is a compound (made of carbon and oxygen atoms).
• Oxygen gas ($O_2$) is an element (made of oxygen molecules, each molecule has two oxygen atoms).

1. Analyze each option:

• Option 1: Silver and oxygen gas are elements, not compounds. So this is incorrect.
• Option 2: All (water, silver, $CO_2$, $O_2$) are matter. Water and $CO_2$ are compounds; silver and $O_2$ are elements. All contain atoms (water has H and O atoms, silver has Ag atoms, $CO_2$ has C and O atoms, $O_2$ has O atoms). This matches.
• Option 3: Water and $CO_2$ are compounds, not elements. So this is incorrect.
• Option 4: Compounds are made of two or more different elements, so "compounds made of one type of element" is wrong. Also, oxygen gas is a diatomic molecule, not "pure atoms" in the sense of single atoms (silver is made of single atoms, but oxygen gas is $O_2$). So this is incorrect.

Answer:

B. They are each made of matter. Some are compounds and some are elements. They all contain atoms.