Answer
[tex]\text{moles = }\frac{\text{mass of the element or molecule}}{\text{atomic mass or molecular mass}}=\text{ }\frac{500\text{ g Zn}}{65.38\text{ g/mol}}=7.64\text{ moles of Zn}[/tex]Don't forget: the atomic mass of Zn you read it from Periodic Table
