Can someone help please

a. 650 moles of S

b. 60 grams of FeS₂

Explanation:

Fe + 2S → FeS₂

from the mole ratio 1 mole of S yields mole of FeS₂

a. ∴ 650 moles of S is required to produce 325 moles of FeS₂

b.  0.5 mole of S yields 0.25 mole of FeS₂

molar mass of FeS₂ = 120gmol⁻¹

mass of FeS₂ = 120gmol⁻¹ ₓ 0.25mol

                      = 60grams

3 1/4 %

explanation:

8 m/s because for him to get the same amount of energy as ray is putting out, bobby, who weighs half as much as ray, needs to run twice as fast.