Tough question, I would suggest using Google maybe, or just plain out asking your science teacher.
The chemical equation needs to be balanced so that it follows the law of conservation of mass.
Isotopes are basically from the same element. In terms of subatomic particles of the element, the isotopes will then basically have the same number of protons. The electrons also have to be same in number given that the elements are in neutral charges.
We are then left with neutrons, which is one of the subatomic particles residing in the nucleus of an atom.
Thus, the answer is NEUTRONS.
Answer:
C3F7
'Tri' means 3
Tricarbon means 3 carbon
"Hepta" means 7
Fluoridez molecular formula is "F"
hence F7
Percent composition by mass is calculated (mass of element within compound)/(mass of compound)*100. The lower the total molar mass of the compound, the greater the percent composition of sulfur. In this case, MgS would be that compound, since Mg has the lowest molar mass of the four elements bonded to S.