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 641: The most abundant element on the earth's crust is Options:
  A) nitrogen
  B) hydrogen
  C) oxygen
  D) flourine
  Show Answer
  The correct answer is C .
• Question 642:

  In the reaction between sodium hydroxide and tetraoxosulphate (VI) solutions, what volume of 0.5 molar sodium hydroxide would exactly neutralize 10cm${}^3$ of 1.25 molar tetraoxosulphate (vi) acid?

  Options:
  A) 25cm${}^3$
  B) 10cm${}^3$
  C) 20cm${}^3$
  D) 50cm${}^3$
  Show Answer
  The correct answer is D .
• Question 643: An organic compound contains 60% carbon, 13.3% hydrogen and 26.7% oxygen. Calculate the empirical formula
  rn(C=12,H =1, O=16) Options:
  A) C ₅H ₁₂O
  B) C ₃H ₈O
  C) C ₆H ₁₃O ₂
  D) C ₄H ₉O
  Show Answer
  The correct answer is B .
• Question 644:

  Chlorine, consisting of two isotopes of mass numbers 35 and 37, has an atomic mass of 35.5.

  The relative abundance of the isotope of mass number 37 is?

  Options:
  A) 20
  B) 25
  C) 50
  D) 75
  Show Answer
  The correct answer is B .
• Question 645:

  In order to electroplate spoon with silver, the arrangement of the electrolytic cell is?

  Options:
  A) the anode is a silver rod and the cathode is the spoon
  B) the anode is the spoon and the cathode is a silver rod
  C) the electrolyte is silver trioxonitrate(v)( solution and the cathode is a silver rod.
  D) the electrolyte is silver trioxonitrate(v) solution and the anode is the spoon
  Show Answer
  The correct answer is A .
• Question 646:

  Duralumin consists of aluminum, copper?

  Options:
  A) Zinc and Gold
  B) Lead and Manganese
  C) Nickel and Silver
  D) Manganese and Magnesium
  Show Answer
  The correct answer is D .
• Question 647:

  Which of the following reactions is an oxidation process?

  Options:
  A) 2H${}^{+}$ + 2e${}^{-}$ $\to$ H${}_2$
  B) 2O${}^{2-}$ + 4e${}^{-}$ $\to$ O${}_2$
  C) OCl${}^{-}$ + H${}_2$O + 2e${}^{-}$ $\to$ 2OH${}^{-}$ + Cl${}^{-}$
  D) Cl + e${}^{-}$ $\to$ Cl${}^{-}$
  Show Answer
  The correct answer is B .
• Question 648: Which of the following substance is a mixture? Options:
  A) Granulated sugar
  B) Sea-water
  C) Sodium chloride
  D) Iron fillings
  Show Answer
  The correct answer is B .
• Question 649:

  Which of the gas laws does this graph illustrate?

  Options:
  A) Boyle
  B) Charles
  C) Gay-Lussac
  D) Graham
  Show Answer
  The correct answer is B .
• Question 650:

  Which of the following mixtures is an example of a colloid?

  Options:
  A) Milk
  B) Orange juice
  C) Saltwater
  D) Sugar dissolved in water
  Show Answer
  The correct answer is A .