1What is a molecule? Give two examples.
2What is a molecular formula? What does \( \mathrm{H_2O} \) show?
3Write the molecular formula of aluminium chloride by the criss-cross method.
4Write the formula of calcium oxide. Which rule is used?
5Why does calcium bicarbonate need a bracket when sodium bicarbonate does not?
6What facts can be learnt from a molecular formula?
7What is atomic weight? Find the atomic weight of sodium.
8Calculate the molecular weight of sulphuric acid, \( \mathrm{H_2SO_4} \). (H = 1, S = 32, O = 16)
9Calculate the molecular weight of magnesium hydroxide, \( \mathrm{Mg(OH)_2} \). (Mg = 24, O = 16, H = 1)
10How is atomic weight different from molecular weight?