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 651:

  What current in amperes will deposit 2.7g of aluminium in 2 hours?

  [Al = 27, F = 96 500 C mol^-1]

  Options:
  A) 32
  B) 8
  C) 4
  D) 16
  Show Answer
  The correct answer is C .
• Question 652: A pure solid usually melts? Options:
  A) over a wide range of temperature
  B) over a narrow range of temperature
  C) at a lower temperature than the impure one
  D) at the same temperature as the impure one
  Show Answer
  The correct answer is B .
• Question 653: Detergents are more advantageous than soaps in hard water districts because Options:
  A) on treatment with hard water they either form soluble calcium salts or do not react with calcium ion
  B) on treatment with hard water they form soluble calcium salts
  C) on treatment with hard water they form sodium salts
  D) on treatment with hard water they are converted into soaps
  E) on treatment with hard water they form more lather than soaps does
  Show Answer
  The correct answer is A .
• Question 654: The mathematical expression of PH is Options:
  A) log ₁₀[OH^-]
  B) log ₁₀1/[H ₃ O⁺]
  C) log ₁₀[H ₃ O⁺]
  D) log ₁₀1/[OH ^-]
  Show Answer
  The correct answer is B .
• Question 655: The reaction of an alkene with hydrogen in the presence of catalyst is Options:
  A) a substitution reaction
  B) an oxidation reaction
  C) a nucleophilic reaction
  D) an addition reaction
  Show Answer
  The correct answer is D .
• Question 656:

  The heat of formation of ethene, C${}_2$H${}_4$ is 50 kJmol${}^{-1}$, and that of ethane, C${}_2$H${}_6$ is -82kJmol${}^{-1}$. Calculate the heat evolved in the process:

  C${}_2$H${}_4$ + H${}_2$ $\to$ C${}_2$H${}_6$

  Options:
  A) -122kJ
  B) -132kJ
  C) -88kJ
  D) -60kJ
  Show Answer
  The correct answer is B .
• Question 657:

  The only metal that is anti-bacterial is?

  Options:
  A) Iron
  B) Sodium
  C) Alluminium
  D) Copper
  Show Answer
  The correct answer is D .
• Question 658: The ion that can be used as an oxidizing agent is Options:
  A) Au³⁺
  B) Fe³⁺
  C) F^-
  D) Ca²⁺
  Show Answer
  The correct answer is C .
• Question 659:

  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 660:

  When cathode rays are deflected onto the electrode of an electrometer, the instrument becomes?

  Options:
  A) Bipolar
  B) Negatively charged
  C) Positively charged
  D) Neutral
  Show Answer
  The correct answer is B .