Question

the number of moles is calculated by dividing mass by

Explanation:

The formula for calculating the number of moles ($n$) is $n=\frac{m}{M}$, where $m$ is the mass of the substance and $M$ is the molar mass (the mass per mole of a substance). So, to find the number of moles, mass is divided by molar mass.

Answer:

molar mass