West African Examinations Council
WASSCE Chemistry · Paper 2 — Essay
Written answers, marked against a rubric.
8 exam-style questions, written to the West African Examinations Council format and free to read. The answers are here too — what they do not tell you is how many you would get right with a clock running.
1. (a) What is meant by a homologous series? State three characteristics of one. [6 marks]
(b) Write the structural formulae of the first three members of the alkane series and name each. [6 marks]
(c) Describe a chemical test, giving the reagent and the observation, that would distinguish between ethane and ethene. [8 marks]
2. (a) Define the terms atomic number and mass number. [4 marks]
(b) An element X has atomic number 17 and mass number 35. State the number of protons, neutrons and electrons in one atom of X, and write its electronic configuration. [8 marks]
(c) Explain why isotopes of an element have identical chemical properties but different physical properties. [8 marks]
3. (a) Distinguish between ionic and covalent bonding. [4 marks]
(b) Using dot-and-cross diagrams described in words, explain the bonding in (i) sodium chloride and (ii) methane. [10 marks]
(c) Give two reasons why sodium chloride conducts electricity when molten but not when solid. [6 marks]
4. (a) Define electrolysis and state what is meant by an electrolyte. [4 marks]
(b) Describe what is observed at each electrode during the electrolysis of dilute sodium chloride solution using inert electrodes, and write the equation for each electrode reaction. [10 marks]
(c) State three industrial applications of electrolysis. [6 marks]
5. (a) State Avogadro's law. [3 marks]
(b) 12.0 g of magnesium reacts completely with excess dilute hydrochloric acid. Calculate (i) the number of moles of magnesium used and (ii) the volume of hydrogen produced at s.t.p. (Mg = 24; molar volume at s.t.p. = 22.4 dm³) [10 marks]
(c) Explain why the volume of a gas must be quoted with its temperature and pressure. [7 marks]
Reading these is not the same as sitting them.
Every question above is answerable given time. The exam does not give you time. Sit the whole paper on the real clock and the number you get back is the one that means something.
Sit it against the clock — freeExampaper is an independent study service. It is not affiliated with, endorsed by, or connected to WAEC, NECO, JAMB or any examination body. Exam names and subject titles are used only to describe what each paper is for.