Chemistry 2018 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.

11Ethene is produced from ethanol by

  • A. decomposition
  • B. hydrolysis
  • C. ozonolysis
  • D. dehydration

12.  Consider the following equilibrium reaction: 2AB2(g)+B2(g)2AB3(g)2AB2(g)+B2(g)→2AB3(g)ΔH=XkJmol1ΔH=−XkJmol−1. The backward reaction will be favored 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 500cm3cm3 of 0.005moldm3moldm−3 H2SO4H2SO4? ( H = 1, S = 32.0, O=16.0)

  • A. 0.490g
  • B. 0.049g
  • C. 0.245g
  • D. 0.0245g

14.  Pure water can be made to boil at a temperature lower than 100°C by

  • A. reducing its quantity
  • B. decreasing the external pressure
  • C. distilling it
  • D. increasing the external pressure

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At what temperature does the solubility of KNO3KNO3  equal that of NaNO3NaNO3?   

  • A. 0°C
  • B. 20°C
  • C. 30°C
  • D. 40°C

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 substance X was added to a solution of bromine water, the solution became colourless. X is likely to be

  • A. propane
  • B. propanoic acid
  • C. propyne
  • D. propanol

18. The preferential discharge of ions during electrolysis is influenced by the 

  • A. mechanism of electrolysis
  • B. electrolytic reactions
  • C. nature of the electrode
  • D. type of electrolytic cell

19. The valence electrons of 12Mg12Mg are in the

  • A. 3s orbital
  • B. 2pxx
  • C. 2s orbital
  • D. 1s orbital

20. Stainless steel is an alloy comprising of

  • A. Fe and C
  • B. Fe and Ni
  • C. Fe, C and Ni
  • D. Fe, C and Al

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