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 461: The minimum volume of oxygen required for the complete combustion of a mixture of 10cm ³ of CO and 15 cm ³ of H ² is Options:
  A) 25.0cm³
  B) 12.5 cm³
  C) 10.0 cm³
  D) 5.0cm³
  Show Answer
  The correct answer is C .
• Question 462:

  Which of the following properties increases from left to right along the period but decreases down the group in the Periodic Table?

  I. Atomic Number   ii. Ionization energy  iii. Metallic character  iv. Electron affinity

  Options:
  A) ii and iii only
  B) ii and iv only
  C) iii and iv only
  D) i and ii only
  Show Answer
  The correct answer is B .
• Question 463: An element X forms the following compounds with chlorine; XCl₄, XCl₃, XCl₂. This illustrates the Options:
  A) law of multiple proportions
  B) law of chemical proportions
  C) law of simple proportions
  D) law of conservation of mass
  E) law of definite proportions
  Show Answer
  The correct answer is A .
• Question 464: Farmlands affected by crude-oil spillage can be decontaminated by Options:
  A) Adding acidic solution
  B) Using aerobic bacteria
  C) Pouring water on the affected water area
  D) Burning off the oil from the area
  Show Answer
  The correct answer is B .
• Question 465:

  A gas that will turn orange potassium heptaoxodichromate (lV) solution to clear green is?

  Options:
  A) sulphur (lV) oxide
  B) hydrogen sulphide
  C) sulphide (lV) oxide
  D) hydrogen chloride
  Show Answer
  The correct answer is A .
• Question 466: POlyvinyl chloride is used to produce Options:
  A) bread
  B) pencils
  C) ink
  D) pipes
  Show Answer
  The correct answer is D .
• Question 467: A major effect of oil pollution in coastal waters is the? Options:
  A) destruction of marine life
  B) desalination of the water
  C) increase in the acidity of the water
  D) detoxification of the water
  Show Answer
  The correct answer is C .
• Question 468: If the ONLY pollutants found in the atmosphere over a city are oxides of nitrogen, suspended lead compounds. carbon monoxide and high levels of methane, the probable source(s) of the pollution must be? Options:
  A) automobile exhaust and biological decomposition
  B) combustion of coal and automobile exhaust
  C) biological decomposition only
  D) combustion of coal, automobile exhaust and biological decomposition
  E) combustion of coal and biological decomposition
  Show Answer
  The correct answer is B .
• Question 469:

  Which of the following alkanes has a straight-chain structure?

  Options:
  A) Cyclopentane (C5H10)
  B) Isobutane (C4H10)
  C) 2 - methyl propane (C4H10)
  D) Pentane (C5H12)
  Show Answer
  The correct answer is D .
• Question 470: A suitable reagent for distinguishing between ethanoic acid ethanol is Options:
  A) bromine water
  B) Fehling's solution
  C) sodium hydrogentrioxocarbonate (IV)
  D) ammoniacal silver trioxonitrate (V)
  Show Answer
  The correct answer is C .