Give the formulae of the compounds formed from the following set of elements.

(i) Carbon and hydrogen

(ii) Nitrogen and magnesium

(iii) Sodium and phosphorus

(iv) Potassium and oxygen

(v) Boron and oxygen

(i) Carbon and hydrogen:

CH₄ (methane)

C₂H₆ (ethane)

(ii) Nitrogen and magnesium:

Magnesium nitrate

Formula: Mg₃(NO₃)₂

(iii) Sodium and phosphorus:

Sodium phosphate

Formula: Na₃PO₄

(iv) Potassium and oxygen:

Potassium oxide

Formula: K₂O

(v) Boron and oxygen:

Boron oxide

Formula: B₂O₃