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 921:

  MnO_4(aq) + 8H + 5Fe²⁺ $\to$ Mn²⁺_(aq) + 5Fe³⁺_(aq) + H₂O.

  The oxidation number of manganese in the above reaction changed from

  Options:
  A) +7 to +2
  B) +6 to +2
  C) +5 to +2
  D) +4 to +2
  Show Answer
  The correct answer is A .
• Question 922: A certain liquid has a high boiling point. It is viscous, non-toxic, miscible with water being very hygroscopic. This liquid is most likely to be? Options:
  A) CH₃CH₂CH₂HO
  B) CH₃CHOHCH₃
  C) CH₃CH₂CHOHCH₃
  D) CH₂OHCHOHCH₂OH
  Show Answer
  The correct answer is D .
• Question 923: What is the IUPAC nomenclature of the compound NaCIO? Options:
  A) sodium oxochlorate (I)
  B) sodium chloro (I) oxide
  C) sodium monooxochlorate (II)
  D) sodium chloro (I) monoxide
  Show Answer
  The correct answer is A .
• Question 924: Copper is displaced from the solution of its salts by most metals because it Options:
  A) is a transition element
  B) is at the bottom of the activity series
  C) is very reactive
  D) has completely filled 3d-orbitals
  Show Answer
  The correct answer is B .
• Question 925: 3Cl₂ + 2NH₃ $\to$ N₂ + 6HCl. In the above reaction, ammonia acts as Options:
  A) a reducing agent
  B) an oxidizing agent
  C) an acid
  D) a catalyst
  E) a dry agent
  Show Answer
  The correct answer is A .
• Question 926: A little quantity of trichloromethane (b.pt 60,^oC) was added to a large quantity of ethanol (b.pt 78,^oC). The most probable boiling point of the resultant mixture is from Options:
  A) 69 ^oC - 70 ^oC
  B) 70 ^oC – 74 ^oC
  C) 82 ^oC – 84 ^oC
  D) 60 ^oC – 78 ^oC
  Show Answer
  The correct answer is C .
• Question 927: Which of the following types of reactions takes place between C₂H₄ and the halogens? Options:
  A) Substitution
  B) Polymerization
  C) Addition
  D) Saponification
  E) Oxidation
  Show Answer
  The correct answer is C .
• Question 928: The carbon atoms on ethane are Options:
  A) sp² hybridized
  B) sp³ hybridized
  C) sp⁴ hybridized
  D) sp hybridized
  Show Answer
  The correct answer is B .
• Question 929:

  Addition of sodium chloride to water to form a solution would lead to?

  Options:
  A) increase in freezing point and increase the boiling point
  B) increase in freezing point and decrease the boiling point
  C) decrease in freezing point and decrease the boiling point
  D) decrease in freezing point and increase the boiling point
  Show Answer
  The correct answer is D .
• Question 930:

  The size (diameter) of five elements are in the order R < T < W < X < Y, Y being the largest. If each atom has an electron situated on its circumference, and neglecting other factors, which of the atoms will lose its electron most reluctantly?

  Options:
  A) R
  B) T
  C) W
  D) X
  E) Y
  Show Answer
  The correct answer is A .