A chlorine molecule, Cl2\mathrm{Cl_{2}}Cl2, is about 0.2 nm long.
How many chlorine molecules, placed end to end, would fit along a line 1 mm long?
2×10−72\times10^{-7}2×10−7
5×1035\times10^{3}5×103
5×1065\times10^{6}5×106
5×1095\times10^{9}5×109
53 exam-style questions on Edexcel GCSE Chemistry 2.4 Covalent bonding, covering 2.4.1 Covalent bonding and simple molecules. Each one has a worked solution and a mark scheme showing where the marks go.