Waec 1991 Chemistry Past Questions And Answers
In solution, aminoethanoic acid (glycine) can be represented as NH33 CH2COO. This implies that it
- A. is soluble in all inorganic liquids
- B. can function as a weak acid or a weak base
- C. does not form salt with mineral acids
- D. is highly acidic
(a) Give two reasons why fused alumina is mixed with cryolite in the electrolytic extraction of aluminium.
(b) Write an equation for the reaction of sodium hydroxide with bauxite.
Hydrogen is used for the following except
- A. manufacturing of ammonia
- B. synthesis of hydrochloric acid
- C. extinguishing fire
- D. conversion of coal to petrol
A colourless and odourless gas X burns in oxygen with a pale blue flame.
(a) Suggest two gases which X could be.
(b) Give one chemical test that could be used to confirm which of the two gases X is.
Which of the following elements can from more than one acidic oxide?
- A. Hydrogen
- B. Sulphur
- C. Carbon
- D. Alumium
Which of the following is suitable for determining different isotopes present in an element which exhibits isotopy?
- A. Sensitive weighing balance
- B. Cathoda ray tube
- C. Mass spectrometer
- D. Geiger muller counter
In which of the following is the oxidation number of nitrogen zero?
- A. SO2 and NH3
- B. NaNO3
- C. HNO2
- D. N2
State the atoms represented as shown in the diagram below:
(a) State the relationship between the two atoms.
(b) What is the difference between them?
(c) Give two examples of elements which exhibit the phenomenon illustrated above.
Compounds that have the same molecular formula but different structures are said to be
- A. allotropic
- B. polymorphic
- C. polymeric
- D. isomeric
(a) Name one gaseous hydrocarbon which is
(i) used for welding.
(ii) a major raw material for the plastic industry.
(b) Write the structural formula of the hydrocarbon in (a)(i) above. Name the process by which it can be converted to neoprene rubber.
(c) Potatoes contain a high proportion of carbohydrate.
(i) Give the main product formed when potatoes are dehydrated completely
(ii) Describe how you would convert potatoes to ethanol. State the reactions involved the process and write equation for the final stage of the conversion.
(iii) Draw a labelled diagram of the apparatus you would use to obtain a sample of fairly pure ethanol from the product formed in (c)(ii) above. What is the name given to the technique?