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 21:

  A sample of a substance containing only C and H burns in excess O₂ to yield 4.4g of CO₂

  And 2.7 g of H₂O. The empirical formula of a substance is?(C = 12, O = 16, H = 1)

  Options:
  A) CH₃
  B) CH₂
  C) CH₄
  D) C₂H₂₄
  Show Answer
  The correct answer is A .
• Question 22: In which of the following are the aqueous solutions of each of the substances correctly arranged in order to decreasing acidity? Options:
  A) Ethanoic acid, milk or magnesia, sodium chloride, hydrochloric acid and sodium hydroxide
  B) Ethanoic acid, hydrochloric acid, milk of magnesia, sodium chloride and sodium chloride and sodium hydroxide
  C) Hydrochloride acid, ethanol acid, sodium chloride, milk of magnesia and sodium hydroxide
  D) Hydrochloride acid, sodium hydroxide sodium chloride, ethanol acid, and milk of magnesia
  Show Answer
  The correct answer is C .
• Question 23: The reaction of carbide with water gives Options:
  A) ethyne
  B) ethene
  C) ethane
  D) ethanal
  Show Answer
  The correct answer is A .
• Question 24: Which of the following is NOT true of metals? Options:
  A) They are good conductors of electricity
  B) They ionize by electron loss
  C) Their oxides are acidic
  D) They have high melting points
  Show Answer
  The correct answer is C .
• Question 25: Which of the following metals is passive to concentrated trioxonitrate (V) acid? Options:
  A) Iron
  B) Tin
  C) Copper
  D) Zinc
  Show Answer
  The correct answer is A .
• Question 26:

  The contact process is used for the industrial production of

  Options:
  A) sulfuric acid (H2SO4)
  B) Hydrochloric acid (HCl)
  C) Sodium hydroxide (NaOH)
  D) Calcium oxide (CaO)
  Show Answer
  The correct answer is A .
• Question 27:

  In electrovalency, the oxidation number of the participating metal is always

  Options:
  A) decreasing
  B) increasing
  C) constant
  D) neutral
  Show Answer
  The correct answer is C .
• Question 28:

  The molar enthalpy change accompanying the removal of an electron from a gas phase atom orion in its ground state is called?

  Options:
  A) Electron gain enthalpy
  B) Ionization enthalpy
  C) Enthalpy change
  D) Enthalpic gas removal
  Show Answer
  The correct answer is B .
• Question 29: A particle that contains 11 protons, 12 neutrons and 10 electrons is probably a Options:
  A) neutral non-metal
  B) metallic ion
  C) non-metallic ion
  D) neutral metal
  Show Answer
  The correct answer is B .
• Question 30:

  

  In the diagram above, the purpose of the asbestos to

  Options:
  A) absorb impurities
  B) catalyze the reaction
  C) solidify the gas
  D) dry the gas
  Show Answer
  The correct answer is B .