FORM FOUR POST MOCK KILIMANJARO CHEMISTRY EXAMINATION

SECTION C (15 Marks)
Answer two (2) questions in this section

9. A government agricultural extension officer visited Lupaso and Kyimo villages after discovering that soils in both villages were deficient in essential mineral nutrients. The officer advised farmers in both villages to apply inorganic fertilisers to improve crop production. Farmers from Lupaso Village immediately accepted the advice, whereas those from Kyimo Village refused to use inorganic fertilisers despite the nutrient deficiency in their soils. Using your knowledge of Chemistry appraise the decision made by the farmers of Kyimo Village by giving six (6) convincing reasons that justify their refusal to apply inorganic fertilisers. (15 marks)

10. A factory installed a Downs cell to produce sodium metal from molten sodium chloride. During operation, a technician accidentally replaced pure sodium chloride with a mixture containing sodium chloride and calcium chloride but could not explain why calcium chloride is normally added. Using your knowledge of electrolysis, answer the following questions:
a) Explain why sodium chloride must be molten before electrolysis can occur. (02 marks)
b) State reason(s) why calcium chloride is added to the Downs cell instead of using pure sodium chloride only. (03 marks)
c) Write the half-equations occurring at:
i. Cathode
ii. Anode (03 marks)
d) Explain why sodium and chlorine products are prevented from mixing inside the Downs cell. (02 marks)
e) State four (4) industrial uses of sodium metal. (04 marks)
f) State the function of graphite anode (01 Mark)

11. A district experiences increasing temperatures, prolonged droughts, and unpredictable rainfall. Some leaders attribute these changes entirely to natural climatic variations. Using scientific knowledge:
a) Explain four (4) human activities contributing to climate change (08 marks)
b) Explain two (2) effects of climate change on agriculture (04 marks)
c) Suggest two (2) adaptation strategy for farmer (03 marks)