Chemistry 2020 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.

  1. Which of the following substances is an example of a fine chemical?
  • A. Sodium hydroxide
  • B. Hydrochloric acid
  • C. Ethylene
  • D. Ammonia

2.  The IUPAC name of the compound represented by the structure below is ?

  • A. 2- chloro but-I ,3-diene.
  • B. But-1,3-chlorodiene.
  • C. 2-chloro but-diene.
  • D. 3 -chloro but -1.3-diene.

3.  Which or the following substances is a polypeptide?

  • A. Starch
  • B. Glycogen
  • C. Protein
  • D. Fats

4.  Which or the following products could be formed during incomplete combustion of a hydrocarbon.

i.Carbon ii. Hydrogen III. Carbon (Il) oxide

  • A. I only
  • B. I and II only
  • C. I and III only
  • D. II and III only

 

5. 

  1. What quantity of electrons is lost when one mole of iron (II) ions is oxidized to iron (III) ?
  • A. 0 mole
  • A. 3 moles
  • B. I mole
  • C. 2 moles

6.  What is the mass of silver deposited when 24,125 C of electricity is passed through a solution or silver salt.

[Ag = 108, IF = 96,500 C ]

  • A. 432g
  • B. 108g
  • C. 54g
  • D. 27g

7.  Equal masses of calcium trioxocarbonate(iv) were added to dilute hydrochloric acid at the temperature specified. Under which of the following conditions would the reaction be slowest?

  • A. Calcium trioxocarbonate ( iv ) chips a 20°C
  • B. CalcIum trioxocarbonate (IV) chips at 40°C
  • C. Calcium trioxocarbonate (IV) powder at 20’C
  • D. Calcium trioxocarbonate (IV) powder at 40’C

8.  The high solubility of ethanol in water is due to?

  • A. its low boiling point.
  • B. its low freezing point.
  • C. its covalent nature
  • D. hydrogen bonding

9.  Which of the following pairs of properties of alkali metals decreases down the group?

  • A. First ionization energy and reactivity
  • B. melting point and atomic radius
  • C. Reactivity and electronegativity
  • D. First ionization energy and melting point

10.  The most suitable process of obtaining water from an aqueous solution of sugar i

  • A. Crystallization
  • B. Distillation
  • C. Filtration
  • D. Decantation

11.  Group VIl elements in their combined states are called?

  • A. Halogens
  • B. Anions
  • C. Halide
  • D. Cations

12.  When an ionic bond is broken, bonding electrons are

  • A. shared between participating atoms
  • B. gained by the most electropositive atom
  • C. gained by the most electronegative atom
  • D. lost by both participating atoms

13.  The oxidation state of chlorine in NaClO3is?

  • A. +1
  • B. +3
  • C. +5
  • D. +6

14.  A balanced chemical equation is based on the law of?

  • A. Periodicity
  • B. Constant composition
  • C. Multiple proportion
  • D. Conservation of mass

15.  Which of the following pairs of elements has the greatest difference in electronegativity?

  • A. Na and F
  • B. Na and CI
  • C. Na and Br
  • D. Na and I

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