Resposta :
1) Acetileno (etino) ⇒ H-C≡C-H
C₂H₂ + ⁵/₂ O₂ → 2 CO₂ + H₂O
⁵/₂ mol --------------------------- 1 mol
x --------------------------- 20 mol
x = 50 mol de O₂
2) CH₄ + 2 O₂ → CO₂ + 2 H₂O
1 mol 1 mol
↓ ↓
16 g ------------------------- 44 g
50 g ------------------------- x
x = 137,5 g de CO₂
3) 3 Fe + 4 H₂O → Fe₃O₄ + 4 H₂
3 mol ---------------------------------------------- 4 mol
76 mol ---------------------------------------------- x
x = 101,3 mol de H₂