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 1901: Carbohydrates are large molecules with the molecular formula C _x (H₂O)_y. In which of the following pairs is x not equal to y? Options:
  A) glucose and starch
  B) maltose and starch
  C) sucrose and fructose
  D) maltose and starch
  Show Answer
  The correct answer is A .
• Question 1902:

  

  The IUPAC name of the compound above is
  Options:
  A) 2,2-dimethyl but -1-yne
  B) 2,2-dmethyl but -1-ene
  C) 3,3-dimethyl but -1-ene
  D) 3,3-dimethyl but-1-yne
  Show Answer
  The correct answer is C .
• Question 1903: Which of the following happens during the electrolysis of molten sodium chloride? Options:
  A) Sodium ion loses an electron
  B) Chlorine atom gains an electron
  C) Chlorine ion gains an electron
  D) Sodium ion is oxidized
  E) Chloride ion is oxidized
  Show Answer
  The correct answer is E .
• Question 1904: Cr₂O₇ + 6Fe²⁺ + 14H⁺ → 2Cr³⁺ +6Fe³⁺ + 7H₂O. In the above , the oxidation number of chromium changed from? Options:
  A) +7 to +3
  B) +6 to +3
  C) +5 to +3
  D) -2 to +3
  Show Answer
  The correct answer is A .
• Question 1905: Complete hydrogenation of ethyne yields? Options:
  A) benzene
  B) methane
  C) ethane
  D) ethene
  E) propane
  Show Answer
  The correct answer is C .
• Question 1906: A chemical reaction which the hydration energy is greater than the lattice energy is referred to as Options:
  A) a spontaneous reaction
  B) an endothermic reaction
  C) an exothermic reaction
  D) a reversible reaction
  Show Answer
  The correct answer is C .
• Question 1907: The volume occupies by 1.58g of a gas at s.t.p is 500cm³. What is the relative molecular mass of the gas? (G.M.V at s.t.p = 22.40dm³) Options:
  A) 28
  B) 32
  C) 44
  D) 71
  Show Answer
  The correct answer is D .
• Question 1908:

  

  Changes in the physical in the scheme above.The letter X,Y and Z respectively represent

  Options:
  A) sublimation, condensation and freezing
  B) sublimation, vapourization and solidification
  C) freezing, condensation and sublimation
  D) evaporation, liquefaction and solidification
  Show Answer
  The correct answer is A .
• Question 1909: Nitrogen obtained from the liquefaction of air has a higher density than that obtained from nitrogen containing compounds because the former contains Options:
  A) water vapour
  B) oxygen
  C) carbon (IV) oxide
  D) rare gases
  Show Answer
  The correct answer is D .
• Question 1910: In the industrial production of hydrogen from natural gas, carbon (IV) oxide produced along with the hydrogen is removed by? Options:
  A) washing under pressure
  B) passing the mixture into lime water
  C) using ammoniacal copper (l) chloride
  D) drying over phoshorus (V) oxide
  Show Answer
  The correct answer is C .