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 821: The effect of the presence of impurities such as carbon and sulphur on iron is that they Options:
  A) give it high tensile strenght
  B) make it malleable and ductile
  C) increase its melting point
  D) lower its melting point
  Show Answer
  The correct answer is D .
• Question 822: Sodium metal is always kept under oil because it Options:
  A) Readily reacts with water
  B) Is reduced by atmospheric nitrogen
  C) Reacts vigorously on exposure to air
  D) Reacts with oxygen and carbon (IV) oxide
  Show Answer
  The correct answer is C .
• Question 823: N₂O_4(g) ↔ 2NO_2(g). Increase in total pressure of the equilibrium reaction above will Options:
  A) produce more of NO_2(g) in the mixture
  B) convert all of N₂O_4(g) to NO_2(g)
  C) have no effect on the concentrations of NO_2(g)and N₂O_4(g)
  D) produce more of N₂O_4(g) in the mixture
  Show Answer
  The correct answer is D .
• Question 824:

  When water drops are added to calcium carbide in a container and the gas produced is passed through a jet and lighted, the resultant flame is called an?

  Options:
  A) Oxyethene
  B) Oxyhydrocarbon flame
  C) Oxyacetylene flame
  D) Oxymethane flame
  Show Answer
  The correct answer is C .
• Question 825: On which of the following is the solubility of a gaseous substance dependent? I. Nature of solvent II. Nature of solute III. Temperature IV. Pressure Options:
  A) I, II, III and IV
  B) I and II only
  C) II only
  D) I, III and IV only
  Show Answer
  The correct answer is D .
• Question 826:

  NaCI_(s) + H₂SO_4(I) → HCI_(g) + NaHSO_4(s).

  In the reaction above, H₂SO₄ behaves as?

  Options:
  A) a strong acid
  B) an oxidizing agent
  C) a good solvent
  D) a dehydrating agent
  Show Answer
  The correct answer is A .
• Question 827:

  

  Consider the solubility curves of three salts X, Y and Z given in the diagram. If each solution of the salt contains 200 g, and is heated to 100^oC, which solution or solutions will deposit 100 g of the solute when suddenly cooled to 0^oC?

  Options:
  A) X only
  B) Y only
  C) Z only
  D) X and Z
  E) Y and Z
  Show Answer
  The correct answer is E .
• Question 828: Which of the following samples will react fastest with dilute trioxonitrate (V) acid? Options:
  A) 5 g of lumps of CacO₃ at 25°C
  B) 5 g of powered CacO₃ at 25°
  C) 5 g of lumps of CaCO₃ at 50°C
  D) 5 g of powered CaCO₃ AT 50°C
  Show Answer
  The correct answer is D .
• Question 829: The distance between the nuclei of chlorine atoms in a chlorine molecule is 0.194nm. The atomic radius of chlorine atom is Options:
  A) 0.097nm
  B) 0.914nm
  C) 0.388nm
  D) 2.388nm
  Show Answer
  The correct answer is A .
• Question 830:

  

  The compound above is an

  Options:
  A) alkanone
  B) alkanoate
  C) alkanal
  D) akanol
  Show Answer
  The correct answer is A .