Answer : The molecular formula of the compound will be, 
Explanation :
Empirical formula : It is the simplest form of the chemical formula which depicts the whole number of atoms of each element present in the compound.
Molecular formula : it is the chemical formula which depicts the actual number of atoms of each element present in the compound.
For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.
The equation used to calculate the valency is :
As we are given that the empirical formula of a compound is 
and the molar mass of compound is, 90.09 gram/mol.
The empirical mass of = 1(12) + 2(1) + 1(16) = 30 g/eq
Molecular formula = 
Thus, the molecular formula of the compound will be,
1 is seconds and meters m/s
2 is seconds and meters m/s^2
3 Newton kg/m
4 Kilograms
Hope this helps!
A. The number of valence electrons increases as atomic mass increases. == Generally true for the representative elements since atomic mass generally increases with increasing Z.
B. The reactivity of alkali metals increases as atomic mass increases. == True. Atomic mass increases down the column and so does reactivity
C. The reactivity of the halogens increases as atomic mass increases. == False. Reactivity decreases down the column.
D. The number of valence electrons decreases across a period. == False. In general, the number of valence electrons increases across a period, particularly for the representative elements.
$8.09
Because you multiply and subtract to get the answer
I don't think it's any of the above. Because there is two double carbon bonds and it belongs to an alkene, it should be an ethene molecule.
