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 1091:

  What is the valency of an element with the electronic configuration 2, 8, 7?

  Options:
  A) 7
  B) 1
  C) 2
  D) 3
  Show Answer
  The correct answer is B .
• Question 1092: 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 1093: A piece of sea shell, when dropped into a dilute solution of hydrochloric acid, produces a colourless, odourless gas which turns clear limewater milky. The sea shell contains Options:
  A) sodium chloride
  B) ammonium nitrate
  C) calcium carbonate
  D) calcium chloride
  E) magnesium chloride
  Show Answer
  The correct answer is C .
• Question 1094: Consider the following equation H₂O + 2Fe²⁺ + Cl₂ ↔ 2Fe³⁺ + 2Cl^- + H₂O. The only ion which behaves as an oxidising agent is Options:
  A) Fe²⁺
  B) Cl₂
  C) Fe³⁺
  D) Cl^-
  E) H₂O
  Show Answer
  The correct answer is B .
• Question 1095:

  

  In the diagram above. X is

  Options:
  A) SO₃
  B) SO₂
  C) S
  D) H₂S
  Show Answer
  The correct answer is B .
• Question 1096:

  

  Use the graph above to answer this question.

  A sample, X, solid at room temperature, was melted, heated to a temperature of 358 K and allowed to cool as shown in OPQR. The section PQ indicates that X is

  Options:
  A) a mixture of salts
  B) a hydrated salt
  C) an ionic salt
  D) a pure compound
  Show Answer
  The correct answer is D .
• Question 1097:

  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 1098: Element X has a total of 19 electrons and can react with oxygen to form an oxide. Which of the following statements is NOT true of the oxide of the element? Options:
  A) When exposed to air, it slowy changes to liquid
  B) its solution in water conducts electricity
  C) Its solution in water, on evaporationm gives a white solid
  D) Its solution in water liberates hydroge when in contact with aluminium metal
  E) Its oxide, when stronlgy heated, regenerates the elements X
  Show Answer
  The correct answer is A .
• Question 1099: A few drops of concentrated PCI are added to about 10cm³ of a solution of pH 3.4. The pH of the resulting mixtures is? Options:
  A) less than 3.4
  B) greater than 3.4
  C) unaltered
  D) the same as that of pure water
  Show Answer
  The correct answer is C .
• Question 1100:

  What is the chemical structure of soap and detergent molecules?

  Options:
  A) Hydrophilic head and hydrophobic tail
  B) Hydrophilic head and hydrophilic tail
  C) Hydrophobic head and hydrophobic tail
  D) Hydrophilic tail and hydrophobic head
  Show Answer
  The correct answer is A .