a. In each of the following equations, state which reactant has been oxidised:

i. PbO + H₂ → Pb + H₂O

ii. CO + Ag₂O → 2Ag + CO₂

iii. 2Mg + CO₂ → 2MgO + C

b. In each of the following equations, state which reactant has been reduced:

i. 5CO + I₂O₂ → 5CO₂ + I₂

ii. 2H₂S + SO₂ → 3S + 2H₂O

iii. CH₂ = CH₂ + H₂ → CH₃CH₃