Give three reasons why - carbon dioxide is considered a compound, while carbon - an element.

State what information is provided by the formula of calcium hydroxide - Ca(OH)₂.

Write the symbols of the following elements & radicals along with their valencies.

(a) sodium

(b) magnesium

(c) chlorine [chloride]

(d) nitrate

(e) sulphite

(f) aluminium

(g) oxygen [oxide]

(h) bromine [bromide]

(i) zinc

(j) sulphur [sulphide]

(k) sulphate

(l) hydroxide

(m) calcium

(n) carbonate

(o) potassium

(p) phosphate

(q) iodine [iodide]

Valency list:

(i) 1⁺

(ii) 2⁺

(iii) 3⁺

(iv) 1^-

(v) 2^-

(vi) 3^-

Write the chemical formula of the following -

(a) magnesium oxide

(b) sodium bromide

(c) calcium sulphide

(d) magnesium sulphate

(e) aluminium chloride

(f) zinc oxide

(g) calcium carbonate.