How many moles of fes2 are required to produce 32g of so2?

So, the right answer is

No. of moles of FeS₂ = 0.25 mole

Explanation:

From the balanced

4 FeS2 + 11 O2 → 2 Fe2O3 + 8 SO2

it is clear that 4 mol  FeS₂ react with O₂ to give Fe₂O₃ and 8 mol of SO₂

First, we have to convert mass of SO₂ into No. of moles as following:

SO₂ has molar mass = 64 g/mol

No. of moles of SO₂ = (mass / molar mass) = (32 g / 64 g/mol) = 0.5 mol

we know that  

4 mol  FeS₂  gives→ 8 mol of SO₂

1 mol  FeS₂  gives→ 2 mol of SO₂

??? mol  FeS₂  gives→ 0.5 mol of SO₂

No. of moles of FeS₂ = (0.5 mol * 1 mol ) / 2 mol = 0.25 mol

So, the right answer is

No. of moles of FeS₂ = 0.25 mol

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.