Chemistry 2019 Past Questions | WAEC

Study the following Chemistry past questions and answers for JAMBWAEC  NECO and Post-JAMB. Get prepared with official past questions and answers for upcoming examinations.

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+ 3H2SO4Al2(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

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