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 721:

  In the laboratory preparation of oxygen, the gas cannot be collected by displacement of air because

  Options:
  A) the density of oxygen is greater than that of air
  B) the density of air is nearly the same as that of oxygen
  C) oxygen is a component of air
  D) air is an impure substance
  Show Answer
  The correct answer is A .
• Question 722:

  A colourless organic compound X was burnt in excess air to give two colourless and odourless gases, Y and Z, as products. X does not decolorize blue bromine vapour, Y turns lime milky while Z gives a blue colour with copper (ll) tetraoxosulphate (IV).

  Y and Z are respectively?

  Options:
  A) CO₂ and NH₃
  B) CO and NH₃
  C) SO₂ and H₂O
  D) CO₂ and H₂O
  E) SO₂ and NH₃
  Show Answer
  The correct answer is D .
• Question 723:

  

  Use the following option above to answer this question. Which of the following is the functional group of carboxylic acids?

  Options:
  A) A
  B) B
  C) C
  D) D
  E) E
  Show Answer
  The correct answer is D .
• Question 724:

  If one of the following oxides is heated with hydrogen or carbon using a bunsen burner. it is not reduced to the metal, Which one is it?

  Options:
  A) lead oxide
  B) Magnesium oxide
  C) Copper oxide
  D) Tin oxide
  Show Answer
  The correct answer is B .
• Question 725:

  Which of the following metals cannot replace hydrogen from water or steam?

  Options:
  A) Sodium
  B) Magnesium
  C) Iron
  D) Calcium
  Show Answer
  The correct answer is D .
• Question 726: Which of the following is a measure of the average kinetic energy of the molecules of a substance? Options:
  A) Volume
  B) Mass
  C) Pressure
  D) Temperature
  Show Answer
  The correct answer is D .
• Question 727: Elements in the same period in the periodic table have the same Options:
  A) number of shells
  B) atomic number
  C) chemical properties
  D) physical properties
  Show Answer
  The correct answer is A .
• Question 728: The confirmatory test for alkanoic acids in organic qualitative analysis is the? Options:
  A) turning of wet blue litmus paper red
  B) reaction with alkanols to form esters
  C) reaction with sodium hydroxide to form salt and water
  D) reaction with aqueous Na₂COsp₃ to liberate a gas which turns lime water milky
  Show Answer
  The correct answer is B .
• Question 729: In what way is equilibrium constant for the forward reaction related to that of the reversed reaction? Options:
  A) The additional of the two is expected to be one
  B) The product of the two is expected to be one
  C) The two equilibrium constants are identical
  D) The product of the two is always greater than one
  Show Answer
  The correct answer is A .
• Question 730:

  A sample of a gas exerts a pressure of 8.2 atm when confined in a 2.93 dm³ container at 20°C. The number of moles of gas in the sample is?

  (R = 0.082 litre atm / deg mole)

  Options:
  A) 1.00
  B) 2.00
  C) 3.00
  D) 4.00
  Show Answer
  The correct answer is A .