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 321:

  Which of the following changes is physical?

  Options:
  A) Adding iron filing to aerated water
  B) Adding sodium metal to water
  C) Cooling a solution of Iron (II) sulphate to obtain the hydrated salt
  D) Cooling water to obtain ice
  E) Burning the domestic gas (Utilgas) for cooking
  Show Answer
  The correct answer is D .
• Question 322: Which of the following will produce a solution with pH less than 7 at equivalent point? Options:
  A) HNO ₃ +NaOH
  B) H ₂SO ₄ + KOH
  C) HC +Mg (OH) ₂
  D) HNO ₃ + KOH
  Show Answer
  The correct answer is C .
• Question 323:

  

  An experiment test of the Law of conservation of Mass is illustrated in the diagram. In practice, the flask is weighed before and after reaction between solutions X and Y. Which of the following pairs of solutions will be unsuitable for the experiments

  Options:
  A) X = hydrochloric acid; Y = silver nitrate
  B) X = barium chloride; Y = dilute sulphuric acid
  C) X = hydrochloric acid; Y = sodium hydroxide
  D) X = hydrochloric acid; Y = lead nitrate
  E) X = hydrochloric acid; Y = sodium carbonate
  Show Answer
  The correct answer is E .
• Question 324:

  According to Charles' law, the volume of a gas becomes zero at

  Options:
  A) 0°C
  B) -100°C
  C) -273°C
  D) -373°C
  Show Answer
  The correct answer is C .
• Question 325:

  Which of the following reactions is an oxidation process?

  Options:
  A) 2H${}^{+}$ + 2e${}^{-}$ $\to$ H${}_2$
  B) 2O${}^{2-}$ + 4e${}^{-}$ $\to$ O${}_2$
  C) OCl${}^{-}$ + H${}_2$O + 2e${}^{-}$ $\to$ 2OH${}^{-}$ + Cl${}^{-}$
  D) Cl + e${}^{-}$ $\to$ Cl${}^{-}$
  Show Answer
  The correct answer is B .
• Question 326: Which of the following compounds can be represented by the molecular formula C₂H₆O? Options:
  A) Propanel
  B) Ethanol
  C) Methanoic acid
  D) Glucose
  Show Answer
  The correct answer is B .
• Question 327:

  Which noble gas is radioactive and is produced as a decay product of uranium and thorium?

  Options:
  A) Argon
  B) Krypton
  C) Radon
  D) Neon
  Show Answer
  The correct answer is C .
• Question 328: Synthetic rubber obtained by the polymerization of chlorobutadiene in the presence of sodium is called? Options:
  A) teflon
  B) isoprene
  C) polythene
  D) neoprene
  Show Answer
  The correct answer is D .
• Question 329: The atomic number of an element whose cation, X²⁺, has the ground state electronic configuration 1s²2s²2p⁶3s²2p⁶ is? Options:
  A) 16
  B) 18
  C) 20
  D) 22
  E) 24
  Show Answer
  The correct answer is C .
• Question 330: How will a metal X, which reacts explosively with air and with dilute acids be best extracted from its ores? Options:
  A) Electrolysis of solution of its salts
  B) Decomposition of its oxides
  C) Displacement from solution by an alkali metal
  D) Electroiysis of fused salt
  Show Answer
  The correct answer is D .