(a) Define the following in terms of gain or loss of hydrogen with one example each:
(i) Oxidation (ii) reduction
(b) When a magnesium ribbon is heated, it burns in air to form magnesium oxide. Write a balanced chemical equation for this reaction. Name (i) substance oxidised, and (ii) substance reduced.

Oxidation is the removal of hydrogen and reduction is the addition of hydrogen.

This is demonstrated by an example as foloows:

Fe₂O₃ + 3CO → 2Fe + 3CO₂

In the reaction above, Fe got reduced while Carbon got oxidized by gaining oxygen.

(b) Chemical equation for burning of magnesium ribbon:

2Mg + O₂→ 2MgO

(i) Substance oxidized is Mg (ii) Substance reduced is O₂