Calculating Ions presents?

Question

The human enzyme alcohol dehydrogenase, contains Zn 2+ ions. If one molecule of the enzyme weighs 1.328 * 10^(-19) g, and it is 0.327% Zn by mass, how many Zinc ions are present per molecule of enzyme?

a)1
b)2
c)3
d)4
e)5

Answer 1

Atomic weight: Zn=65.4. Let the enzyme be called E.

1.328x10^-19gE/1moleculeE x 0.327gZn/100gE x 1molZn/65.4gZn x 6.02x10^-23ionsZn/1molZn = 4 atoms Zn / 1 molecule enzyme