water
water
Water
H2O or Water
C2h3n
trace elements
The weight will depend on how much of the substance there is.
Minerals
Minerals
Minerals
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.
That depends not on the given concentration percentage (18%) but solely on the quantity (amount) of HCl (or any other) substance!
It is the French term for "net weight", which is the weight of a substance, not including the weight of the container it's in; "gross weight" includes the weight of the substance and the container.