Prelim questions on acids

Try out challenging questions from prelim papers to apply what you have learned about acids: dissociation of hydrogen ions, acid formation,…

Stoichiometry & the mole concept prelim questions

Learn stoichiometry and the mole concept by solving problems taken from O Level prelim papers. Answers and explanations are included.

Dot and cross diagrams of simple molecules

Dot the i's and cross the t's of your dot-and-cross diagrams

Practise how to write chemical formula

Can you infer the formulae of ionic compounds, based on the charges of their constituent ions?