H2O or Water
water
Water
water
C2h3n
trace elements
The weight will depend on how much of the substance there is.
Minerals
Minerals
Minerals
For a chemical compound, ex. ABC: Percent (%) of A is (atomic weight of A x 100)/molecular weight of ABC.
For a chemical compound, ex. ABC: Percent (%) of A is (atomic weight of A x 100)/molecular weight of ABC.
Not completely. The empirical formula of a substance can be determined from its percent composition, but a determination of molecular weight is needed to decide which multiple of the empirical formula represents the molecular formula.