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.
The answer to this question is theory
The 1st one. Fertilizers are like food for plants, and that's what an algae is, sorta. Trout's don't eat algae and if there's too much algae around, it gets dirty and they eventually die because of the amount of bacteria in the algae. It's the same thing if you have a fish tank.
40.0 is the answer, sorry, I had some lag, I would've answered it like 5 minutes ago
Hope I helped
