The accepted concentration of chlorine is 1.00 ppm that is 1 gram of chlorine per million of water.
The volume of water is
.
Since, 1 gal= 3785.41 mL
Thus, 
Density of water is 1 g/mL thus, mass of water will be
.
Since, 1 grams of chlorine →
grams of water.
1 g of water →
g of chlorine and,
of water →86.6 g of chlorine
Since, the solution is 9% chlorine by mass, the volume of solution will be:

Thus, volume of chlorine solution is 9.62\times 10^{2} mL.
It would be MnSO4
The (II) lets you know it’s the form with a 2+ charge and Sulfate has a 2- charge
These will cancel out making it plain MnSO4
If it was manganese (iii) sulfide the answer would be Mn2(SO4)3
1 mole ----------- 6.02x10²³ molecules
? moles --------- 1.9x10²⁵ molecules
moles = 1.9 x 10²⁵ * 1 / 6.02x10²³
= 1.9 x 10²⁵ / 6.02x10²³
= 31.561 moles
hope this helps!
I believe the answer is, 97.992 calories
Neutrons + protons = atomic mass number
I hope this helps!