Chemistry Exam Past Questions and Answers | JAMB, WAEC and NECO

Chemistry is the study of the substances that make up matter. It looks at their properties, how they react with each other, and how these reactions can create new substances.

• Question 81:

  What is the maximum number of electrons that can occupy the second energy level (n=2)?

  Options:
  A) 2 electrons
  B) 18 electrons
  C) 8 electrons
  D) 32 electrons
  Show Answer
  The correct answer is C .
• Question 82:

  Zn + 2HCL ZnCl${}_2$ + H${}_2$

  What happens to zinc in the above reaction?

  Options:
  A) oxidized
  B) a reactant
  C) reduced
  D) a metal
  Show Answer
  The correct answer is A .
• Question 83:

  

  From the diagram above, find the amount of solute deposited when 200 cm³ of the solution is cooled from 55^oC to 40^oC

  Options:
  A) 0.10 mole
  B) 0.20mole
  C) 0.01 mole
  D) 0.02 mole
  Show Answer
  The correct answer is B .
• Question 84: Chromatography is used to separate components of mixtures which differ in their rates of? Options:
  A) diffusion
  B) migration
  C) reaction
  D) sedimentaion
  Show Answer
  The correct answer is B .
• Question 85: Cr₂O₇ + 6Fe²⁺ + 14H⁺ → 2Cr³⁺ +6Fe³⁺ + 7H₂O. In the above , the oxidation number of chromium changed from? Options:
  A) +7 to +3
  B) +6 to +3
  C) +5 to +3
  D) -2 to +3
  Show Answer
  The correct answer is A .
• Question 86: The polymer used in making car rear lights is Options:
  A) perspex
  B) bakeelite
  C) polystyrene
  D) polyacrylonitrile
  Show Answer
  The correct answer is A .
• Question 87: Copper is displaced from the solution of its salts by most metals because it Options:
  A) is a transition element
  B) is at the bottom of the activity series
  C) is very reactive
  D) has completely filled 3d-orbitals
  Show Answer
  The correct answer is B .
• Question 88:

  A chemical process in which there is a gain of electrons is known as?

  Options:
  A) Sublimation
  B) Reduction
  C) Oxidation
  D) Distillation
  Show Answer
  The correct answer is B .
• Question 89:

  The dehydration of CH${}_3$CH${}_2$CH${}_2$CH${}_2$OH will give?

  Options:
  A) HC≡CCH${}_2$CH${}_3$
  B) CH${}_2$≡CH${}_2$CH${}_3$
  C) CH${}_3$C≡CCH${}_3$
  D) CH${}_3$CH=CHCH${}_3$
  Show Answer
  The correct answer is D .
• Question 90: Which experiment led to the measurement of the charge on an electron? Options:
  A) Mass spectrometric experiment
  B) Oil-drop experiment
  C) Scattering α - particles
  D) Discharge-tube experiment
  Show Answer
  The correct answer is B .