Chemistry 2020 Past Questions | JAMB

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.

31.  The chlorinated alkane often used industrially to remove grease is?

  • A. Tetrachloromethane
  • B. Chloromethane
  • C. Trichloromethane
  • D. Dichloromethane

32. What mass of water is produced when 8.0g of hydrogen reacts with excess oxygen?

  • A. 8.0g
  • B. 16.0g
  • C. 36.0g
  • D. 72.0g

33. Proteins in acid solution undergo?

  • A. Substitution
  • B. Fermentation
  • C. Hydrolysis
  • D. Polymerisation

34. The general formula for the Alkanals is?

  • A. R2CO
  • B. RCHO
  • C. ROH
  • D. RCOOR

35. When cathode rays are deflected onto the electrode of an electrometer, the instrument becomes?

  • A. Bipolar
  • B. Negatively charged
  • C. Positively charged
  • D. Neutral

36. When a solid substance disappears completely as a gas on heating, the substance is said to have undergone?

  • A. Sublimation
  • B. Crystallization
  • C. Distillation
  • D. Evaporation

37. An electron can be added to a halogen atom to form a halide ion with?

  • A. 8 valence electrons
  • B. 7 valence electrons
  • C. 2 valence electrons
  • D. 3 valence electrons

38. Aluminum hydroxide is used in the dyeing industry as a?

  • A. Dye
  • B. Dispersant
  • C. Salt
  • D. Mordant

39. The most important element on the earth’s crust is?

  • A. Nitrogen
  • B. Hydrogen
  • C. Oxygen
  • D. Fluorine

40. To obtain pure carbon(ii)oxide from its mixture with carbon(iv)oxide, the mixture should be?

  • A. Passed over heated copper(ii)oxide
  • B. Bubbled through water
  • C. Bubbled through conc H2SO4
  • D. Bubbled through conc NAOH

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