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 281:

  Benzene can be converted to its derivative toluene by the addition of a methyl group. The reaction is an example of

  Options:
  A) Nucleophilic substitution
  B) Elimination reaction
  C) Electrophilic substitution
  D) Addition reaction
  Show Answer
  The correct answer is C .
• Question 282:

  In which of the following will hydrogen form ionic compound?

  Options:
  A) HCL
  B) NaH
  C) NH${}_3$
  D) CH${}_4$
  Show Answer
  The correct answer is B .
• Question 283: How many unpaired electron are in the p-orbitals of a fluorine atom? Options:
  A) 3
  B) $0$
  C) 1
  D) 2
  Show Answer
  The correct answer is C .
• Question 284: The atom of an element X is represented as _z^yX. The basic chemical properties of X depends on the value of Options:
  A) Y
  B) Z
  C) Y - Z
  D) Z - Y
  Show Answer
  The correct answer is B .
• Question 285:

  A compound contains 40.0% carbon 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180, find the molecular formula.

  [H = 1, C = 12, O = 16]

  Options:
  A) CH₂O
  B) C₃H₆O₃
  C) C₆H₁₂O₆
  D) C₆H₁₂O₃
  Show Answer
  The correct answer is C .
• Question 286:

  N${}_2$O${}_4$⇔ 2NO${}_2$ ( = -ve)

  From the reaction above, which of these conditions would produce the highest equilibrium yield forN${}_2$O${}_4$?

  Options:
  A) Low temperature and high pressure
  B) Low temperature and low pressure
  C) high temperature and low pressure
  D) high temperature and high pressure
  Show Answer
  The correct answer is A .
• Question 287:

  What is the product of the electrolysis of aqueous sodium chloride (NaCl) using inert electrodes?

  Options:
  A) Hydrogen gas at the cathode and chlorine gas at the anode
  B) Hydrogen gas at the cathode and oxygen gas at the anode
  C) Sodium metal at the cathode and chlorine gas at the anode
  D) Sodium metal at the cathode and oxygen gas at the anode
  Show Answer
  The correct answer is A .
• Question 288:

  A certain hydrocarbon on complete combustion at s.t.p produced 89.6dm${}^3$ of CO${}_2$ and 54g of water. The hydrocarbon should be

  Options:
  A) C${}_6$H${}_6$
  B) C${}_4$H${}_{10}$
  C) C${}_5$H${}_{10}$
  D) C${}_4$H${}_6$
  Show Answer
  The correct answer is D .
• Question 289: An isomer of C₅H₁₂ is Options:
  A) 2–ethyl butane
  B) butane
  C) 2–methyl butane
  D) 2–methyl propane
  Show Answer
  The correct answer is C .
• Question 290: Methanoic acid mixes with water in all proportions and has about the same boiling point as water which of the following methods would you adopt to obtain pure water from a mixture of stand, water and methanoic acid? Options:
  A) fractional distillation
  B) filtration followed by distillation
  C) neutralization with sodium hydroxide followed by distillation
  D) esterification with ethanol followed by distillation
  E) neutralization with sodium hydroxide followed by filtration
  Show Answer
  The correct answer is B .