WAEC Chemistry Questions and Answers 2020. In this article, you will find the 2020 WAEC Chemistry questions and answer, how the West African Examinations Council (WAEC) sets Chemistry questions and how to answer them.
It is important to understand the WAEC Chemistry questions before choosing answers. This is because some questions are so confusing such that if one is not careful, wrong answers would be mistaken for correct ones.
WAEC Chemistry Answers 2020 (Theory and Objectives)
1. Which of the following raw materials is used in the plastic industry?
2. Which of the following organic compounds can undergo both addition and substitution reactions?
3. Which of the following equations represents a radox reaction?
(a) AgNO3(aq) + KCI(aq) → AgCI(s) + KNO3(aq)
(b) HNO3(aq) + NaOH(aq) →NaOH(aq) → NaNO3(aq) + H2O(l)
(c) CaCO3(s) → CaO(s) + CO2(g)
(d) 2H2S(s) + SO2(g) → 2HO2 + 3S(g)
4. The process of extraction of iron from its ore is
5. What is the solubility of a salt of 0.4g of it is obtained on evaporating 200 cm3 of its saturated solution to dryness?
(a) 0.08 gdm-3
(b) 2.00 gdm-3
(c) 8.00 gdm-3
(d) ) 80.00 gdm-3
6. An acidic salt has
(a) A double anions in its aqueous solution
(b) a single cation in its aqueous solution
(c) hydrogen ions in its aqueous solution
(d) hydrogen atoms in its aqueous solution
7. A reaction is endothermic if the
(a) Reaction vessel feels cool during the reaction
(b) enthalpy change is negative
(c) bond forming energy exceeds bond breaking energy
(d) heat of formation of reactants exceeds heat of formation of products.
8. In which of the following compounds does hydrogen form ionic compounds?
9. Consider the following reaction equation: Br2 + 2K1→ 2KBr + I2. Bromine is acting as
(a) an oxidizing agent
(b) reducing agent
(c) an acid
(d) a base
10. An organic compound has the emphiical formula CH2. If its molar mass is 42 gmol-1, what is its molecular formula? [H=1.0, C=12.0]
11. Ethane is produced form ethanol by
12. Consider the following equilibrium reaction: 2AB2(g) + B2(g) ↔ 2AB3(g) ∆H = -X kJmol-1 the backward reaction will be favoured by
(a) A decrease in pressure
(b) an increase in pressure
(c) a decrease in temperature
(d) an introduction of a positive catalyst
13. What is the mass of solute in 500 cm-3of 0.00 moldm-3 H2SO4? [H = 1.0, O=16.0, S=32.0]
(a) 0.490 g
(b) 0.049 g
(c) 0.245 g
(d) 0.0245 g
14. Pure water can be made to boil at temperature lower than 100oC by
(a) Reducing its quantity
(b) decreasing the external pressure
(c) distilling it
(d) increasing the external pressure
15. Consider the following sketch of the solubility curve of some substances
At what temperature does the solubility of KNO3 equal that of NaNO3?
0oC (b) 20oC (c) 30oC (d) 40oC
16. When a salt is added to its saturated solution, the salt
(a) Dissolves and the solution becomes super saturated
(b) dissolves and the solution becomes unsaturated
(c) precipitates and the solution remains unchanged
(d) dissolves and crystals are formed.
17. When substances X was added to a solution of bromine water, the solution became colourless. X is likely to be
(b) Propanoic Acid
18. The preferential discharge of ions during electrolysis is influenced by the
(a) Mechanism of electrolysis
(b) electrolysis reactions
(c) nature of the electrode
(d) type of electrolytic cell
19. The valence electrons of 12Mg are in the
(a) 3s orbital
(b) 2Px orbital
(c) 2x orbital
(d) Is orbital
20. Stainless steel is an alloy comprising of
(a) Fe and C
(b) Fe and Ni
(c) Fe, C and Ni
(d) Fe and AI
21. The number of hydrogen ions in 1.0 dm3 of 0.02moldm-3 tetraoxosulphate(VI) acid is [NA = 6.0.2 x 1023]
(a) 1.2 x 1022
(b) 1.2 x 1023
(c) 2.4 x 1023
22. The most suitable substance for putting out petrol fire is
(c) fire blanket
23. The following factors would contribute to environmental pollution except
(a) Production of ammonia
(b) manufacture of cement
24. The position of equilibrium in a reversible reaction is affected by
(a) Particle size of the reactants
(b) vigorous stirring of the reaction mixture
(c) presence of catalyst
(d) change in concentration of the reactants
25. The diagram below illustrates a conical flask containing water and ice
Which of the following statements about the diagram is correct?
(a) The water is at a lower temperature than the ice
(b) Energy is absorbed when the ice changes to water
(c) Energy is released when the ice changes to water
(d) The water molecules vibrate about a fixed point.
WAEC Chemistry Questions and Answers 2020 Essay
Note: The questions and answers above are WAEC repeated questions on Chemistry not exactly the 2020 WAEC questions and answers.
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