Answer: 17) d. 
18. c. The empirical formula of a compound can be twice the molecular formula.
Explanation:
Molecular formula is the chemical formula which depicts the actual number of atoms of each element present in the compound.
Empirical formula is the simplest chemical formula which depicts the whole number of atoms of each element present in the compound.
To calculate the molecular formula, we need to find the valency which is multiplied by each element to get the molecular formula.
The equation used to calculate the valency is:

The empirical mass can be calculated from empirical formula and molar mass must be known.
17. Thus the empirical formula of
should be 
18. The molecular formula will either be same as empirical formula or is a whole number multiple of empirical formula. Thus the empirical formula of a compound can never be twice the molecular formula.
The density of an object or quantity of matter is its mass divided by its volume.
Answer:
Please see the attached pictures.
Explanation:
☆ To ensure that each carbon has 4 bonds, fill the other bonds with Hs.
Answer:
you work out the moles by finding the grand formula mass them you divide the actual mass by the grand formula mass: 25/160 (my grand formula mass is probably slightly different from yours) which I got 0.15625 then I times it by 32(O2) and I got 5. but my periodic table is different. it's whole numbers. ;-)
Explanation:
4.44