What are groups of two or more atoms bonded together that function as a single unit?

Explanation:

There are some options that are correct.

1) Amount of limiting reactant used in a reaction.

It can be calculated from the quantity of the reactants.

2) Amount of excess reactant from a reaction

It can be also calculated from the quantity of the reactants.

3) Theoretical yield of products

Amount of limiting reactant used in a reaction

Amount of excess reactant from a reaction

Theoretical yield of products