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 761: In a flame test for calcium, the flame appears Options:
  A) green when viewed through a blue glass
  B) blue when viewed through a blue glass
  C) orange -red when viewed through a blue glass
  D) brick-red when viewed through a blue-glass
  Show Answer
  The correct answer is D .
• Question 762: Which of the following statements is correct about the periodic table? Options:
  A) Elements in the same group have the same number of electron shells
  B) The non-metallic properties of the elements tend to decrease across each period
  C) Elements in the same period have the same number of valence electrons
  D) The valence electrons of the elements increase progressively across the period
  Show Answer
  The correct answer is D .
• Question 763: Which of the following statements applies during the electroysis of sodium hydroxide sodium hydroxide solution using platinum electrodes? Options:
  A) Na⁺ ions are discharged at the cathode
  B) Hydrogen ions are discharged at the anode
  C) the concentration of sodium hydroxide decrease at both electrode compartments
  D) the concentration of sodium hydroxide increases at the cathode only
  E) the concentration of sodium hydroxide increases at the anode only
  Show Answer
  The correct answer is D .
• Question 764: Oxygen-demanding waste are considered to be a water pollutant because they? Options:
  A) deplete oxygen which is necessary for the survival of aquatic organism
  B) increase oxygen which is necessary for survival of aquatic organism
  C) increase other gaseous substances which are necessary for the survival of aquatic organisms
  D) deplete other gaseous species which is necessary for the survival of aquatic organisms
  Show Answer
  The correct answer is A .
• Question 765: An organic compound containing 40.1% carbon and 6.6% hydrogen has an empirical formula of? Options:
  A) C₂H₄O₂
  B) C₂H₃O₂
  C) CH₂O
  D) CH₃O
  Show Answer
  The correct answer is C .
• Question 766:

  The oxidation state(s) of nitrogen in ammonium nitrite is/are

  Options:
  A) -3, +3
  B) +5
  C) -3, +5
  D) -3
  Show Answer
  The correct answer is A .
• Question 767: In the reaction E+F ↔ G+H, the backward reaction is favoured if the concentration of Options:
  A) F is increased
  B) E is increased
  C) E is reduced
  D) G is reduced
  Show Answer
  The correct answer is C .
• Question 768: The furring of kettles is caused by the presence in water of Options:
  A) calcium hydrogentrioxocarbonate (IV)
  B) calcium trioxocarbonate (IV)
  C) calcium tetraoxosulphate (VI)
  D) calcium hydroxide
  Show Answer
  The correct answer is B .
• Question 769:

  The heat required to raise the temperature of the body by 1k is called?

  Options:
  A) Specific heat
  B) Thermal capacity
  C) Water equivalent
  D) None of the above
  Show Answer
  The correct answer is B .
• Question 770: Which of the following substances are all made by the process of polymerization? Options:
  A) Nylon and soap
  B) Ethanoic acid margarine and ethanol
  C) Nylon and artificial rubber
  D) Soap and butane
  E) Margarine and nylon
  Show Answer
  The correct answer is C .