Question

look at the models of molecules below. select all the elementary substances. bromine cycloocatasulfur ammonia bromomethane oxygen sulfur dioxide

Explanation:

Step1: Recall definition of elementary substance

An elementary substance is made up of only one - type of atom.

Step2: Analyze bromine

Bromine ($Br_2$) is made up of only bromine atoms, so it is an elementary substance.

Step3: Analyze cyclooctasulfur

Cyclooctasulfur ($S_8$) is made up of only sulfur atoms, so it is an elementary substance.

Step4: Analyze ammonia

Ammonia ($NH_3$) is made up of nitrogen and hydrogen atoms, so it is not an elementary substance.

Step5: Analyze bromomethane

Bromomethane ($CH_3Br$) is made up of carbon, hydrogen and bromine atoms, so it is not an elementary substance.

Step6: Analyze oxygen

Oxygen ($O_2$) is made up of only oxygen atoms, so it is an elementary substance.

Step7: Analyze sulfur dioxide

Sulfur dioxide ($SO_2$) is made up of sulfur and oxygen atoms, so it is not an elementary substance.

Answer:

Bromine, Cyclooctasulfur, Oxygen