Chemistry 2019 Past Questions | WAEC
16. The properties of a good primary standard include the following except?
- A. High molecular mass
- B. low molecular mass
- C. high degree of purity
- D. readily available
17. What is the solubility of a salt X at 25ºC if the saturated solution of the salt contains 0.28g in 100cm3 of the solution in mol\dm3?
[ X = 56.0g ]
- A. 0.05
- B. 0.10
- C. 2.60
- D. 2.80
18. Vinegar is an aqueous solution of?
- A. Hydrochloric acid
- B. ethanediol acid
- C. ethanoic acid
- D. hydrofluoric acid
19. which of the following solutions containing one mole per dm33of the compound would have the lowest PH?
- A. ethanoic acid
- B. hydrochloric acid
- C. sodium chloride
- D. sodium hydrogentrioxocarbonate(iv)
20. A sample of air was bubbled into water. The PH of the water slowly changed from 7 to 6. Which of the following gases in the samples caused the change?
- A. carbon(iv)oxide
- B. carbon(ii)oxide
- C. nitrogen
- D. oxygen
21. The most suitable indicator for the reaction between NaOH and HCOOH is?
- A. bromocresol
- B. methyl orange
- C. methyl red
- D. phenolphthalein
22. consider the following reaction equation: 2Al(OH)3+ 3H2SO4→Al2(SO4)3(aq)+6H2 How many moles of tetraoxosulphate(vi)acid is needed to produce 0.5mol of aluminium tetraoxosulphate(vi)?
- A. 0.5
- B. 1.0
- C. 1.5
- D. 3.0
23. which of the following pairs of substances has the highest heat of neutralization?
- A. strong acid and strong base
- B. weak acid and weak base
- C. strong acid and weak base
- D. weak acid and strong base
24. When quicklime dissolves in water?
- A. heat is absorbed
- B. heat is evolved
- C. oxygen is liberated
- D. hydrogen is given off
25. If the value of ΔH is positive for a reaction, it means that the reaction is?
- A. exothermic
- B. endothermic
- C. spontaneous
- D. slow
26. Which of the following compounds is formed by the oxidation of ethanol?
- A. C2H4CO2H
- B. C22H5CO2H
- C. CH3OH
- D. CH3CO2H
27. What is the name of the gas liberated when diluted hydrochloric acid is added to iron(ii)sulphide?
- A. turns lime water milky
- B. decolorizes bromine water
- C. gives a pop sound
- D. turns lead(ii)ethanoate paper black
28. An organic compound contains 72% carbon, 12% hydrogen and 16% oxygen by mass. What is the empirical formula of the compound?
[ H = 1.0. C = 12.0, O = 16.0 ]
- A. C3H8O
- B. C6H12O
- C. C6H12O2
- D. C12H12O11
29. When excess chlorine is mixed with ethane at room temperature, the product formed is?
- A. 1,2-dichloroethane
- B. 1,2-dichloroethene
- C. 1,1-dichloroethane
- D. 1,1-dichloroethene
30. which of the following reagents could be used to distinguish between propan-1-ol and propan-2-ol
- A. H+ / K2Cr2O7
- B. I22 / OH-
- C. CH33COOH
- D. NaCl
