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 781:

  The periodic classification is an arrangement of the elements

  Options:
  A) atomic weights
  B) isotopic weights
  C) molecular weights
  D) atomic numbers
  Show Answer
  The correct answer is D .
• Question 782: Calculate the mass, in kilograms, of magnesium produced by the electrolysis of magnesium (II) chloride in a cell operating for 24 hours at 500 amperes. Options:
  A) 2.7
  B) 5.4
  C) 10.8
  D) 21.7
  Show Answer
  The correct answer is B .
• Question 783:

  Which of the following is a non-metal that remains liquid at room temperature?

  Options:
  A) Chlorine
  B) Phosphorus
  C) Bromine
  D) Helium
  Show Answer
  The correct answer is C .
• Question 784: The saponification of an alkanoate to produce soap and alkanol involves Options:
  A) dehydration
  B) esterification
  C) hydrolysis
  D) oxidation
  Show Answer
  The correct answer is C .
• Question 785: Mortar is NOT used for under-water construction because Options:
  A) it hardens by lose of water
  B) its hardening doe not depend upon evaporation
  C) it requires concrete to harden
  D) it will be washed away by the flow of water
  Show Answer
  The correct answer is A .
• Question 786:

  A quantity of electricity liberates 3.6g of Silver from its salt. What mass of aluminium Will be liberated from its salt by the same quantity of electricity? [Al = 27, Ag = 108].

  Options:
  A) 2.7g
  B) 1.2g
  C) 0.9g
  D) 0.3g
  Show Answer
  The correct answer is A .
• Question 787:

  What is the concentration of a solution containing 2g of NaOH in 100cm³ of solution?

  [Na=23, O=16, H=1]

  Options:
  A) 0.05 moldm^-3
  B) 0.30 moldm^-3
  C) 0.50 moldm^-3
  D) 0.40 moldm^-3
  Show Answer
  The correct answer is C .
• Question 788: Which of the following metals is the least reactive? Options:
  A) Pb
  B) Sn
  C) Hg
  D) Au
  Show Answer
  The correct answer is D .
• Question 789: The function of zinc electrode in a galvanic cells is that it Options:
  A) undergoes reduction
  B) serves as the positive electrode
  C) production electons
  D) uses up electrons
  Show Answer
  The correct answer is C .
• Question 790:

  A substance that is used as a ripening agent for fruits is

  Options:
  A) ethene
  B) propane
  C) methane
  D) butane
  Show Answer
  The correct answer is A .