What is the percent composition of iron (II) sulfate hexahydrate?
a) 4.2% Fe; 4.2% S; 41.6% O; 50.0% H
b) 16.7% Fe; 16.7% S; 66.6% O
c) 21.5% Fe; 12.3% S; 24.6% O; 41.6% H
d) 21.5% Fe; 12.3% S; 61.5% O; 4.7% H
e) 36.8% Fe; 21.1% S; 42.1% O