This question was not popular among the candidates but most of the candidates who answered the question performed well. They properly defined weathering as the gradual disintegration of rocks in situ by either physical, mechanical, chemical or biological processes. Most candidates who answered the question were able to correctly mention the processes of chemical weathering but were unable to describe the processes such as:

- solution: entails rain water dissolving particles to give a solution. This solution on penetration into the cracks of rocks and joints expands the crack further, thus enabling wider surface for the penetration of water into the rock resulting in further dissolution of rocks e.g. when rain water dissolves calcium carbonate in limestone rock;

- Oxidation: entails the chemical action of oxygen on rocks. This chemical action is pronounced in iron rich rocks to produce oxides of iron which then crumbles readily;

- hydration: entails the formation of weak carbonic acids following the combination of oxygen and rain water’s contact in carbonated rocks e.g. the dissolution of calcium carbonate in limestone rocks;

- chelation involves chemical dissolution of rocks by organic acids following the decay of plant tissues occasioned by bacterial action. The organic solution consequently formed facilitates solubility of certain minerals e.g. iron. Lichens and mosses commonly produce acids that dissolves rocks;

- hydrolysis which involves the chemical reaction of rock minerals different from the original rocks. This could be facilitated by hydrogen. Examples of rocks which are changed through this means are the changing of olivine to serpentine and the changing of feldspar to clay.