(doesn't really matter that it's zinc :) ) It is [latex]0.75*N_A[/latex], where [latex]N_A=6.023*10^{23}[/latex] (in some books 6.022).

4.52 X 10²³ atoms Use Avogadro's number to multiply 0.750 moles times 6.022 X 10²³ atoms. Then divide by 1 atom to get the answer. hope that helped