Question

just like in the cheese sandwich recipe, balanced reactions deal with pieces, numbers of things, not weights of things. which of the following is a number of something?
grams
moles

Explanation:

Grams are a unit of mass (weight), measuring the amount of matter by weight. Moles are a unit that directly counts the number of particles (atoms, molecules, ions, etc.), defined as $6.022 \times 10^{23}$ individual entities, so it represents a number of something.

Answer:

moles