State what is meant by the term 'activity series of metals'. State the most reactive & the least reactive metal from the following - Zn, Ag, Na, Fe, Cu, Pb.

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

Four atoms of hydrogen combine with one atom of carbon to give methane [CH₄]. State the valency of carbon.

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^-