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 71: In the periodic table, what is the property that decreases along the periodic and increases down the group? Options:
  A) Atomic number
  B) Electron affinity
  C) Ionization potential
  D) Atomic radius
  Show Answer
  The correct answer is D .
• Question 72:

  Chlorine gas is commonly used in the production of which of the following industrial compounds?

  Options:
  A) Chlorofluorocarbons (CFCs)
  B) Methane
  C) Ammonia
  D) Ethanol
  Show Answer
  The correct answer is A .
• Question 73:

  How many pi ($\pi$) bonds are there in an alkene with six carbon atoms?

  Options:
  A) 4
  B) 6
  C) 5
  D) 3
  Show Answer
  The correct answer is D .
• Question 74: The importance of sodium aluminate (III) in the treatment of water is to Options:
  A) cause coagulation
  B) neutralize acidity
  C) prevent goitre and tooth decay
  D) kill germs
  Show Answer
  The correct answer is A .
• Question 75: Which of the following is not an alkali? Options:
  A) Ca(OH)₂
  B) NH₃
  C) NaOH
  D) Al(OH)₃
  Show Answer
  The correct answer is B .
• Question 76: When temporary hard water is boiled for sometime in a kettle, the inner surface of the kettle becomes coated with a deposit of Options:
  A) calcium tetraoxosulphate(VI)
  B) calcium trioxocarbonate (IV)
  C) calcium hydrogentrioxocarbonate (IV)
  D) aluminium trioxocarbonate (IV)
  Show Answer
  The correct answer is B .
• Question 77: Which of the following is a measure of the average kinetic energy of the molecules of a substance? Options:
  A) Volume
  B) Mass
  C) Pressure
  D) Temperature
  Show Answer
  The correct answer is D .
• Question 78: Four elements P,Q, R and S have atomic numbers of 4, 10, 12 and 14 respectively . Which of these electrons is a noble gas? Options:
  A) P
  B) Q
  C) R
  D) S
  Show Answer
  The correct answer is B .
• Question 79:

  

  In the solubility curve above, water at 98^oC is saturated with KCL and KCIO₃ What is the percentage of KCL impurity in the crystals formed when the solution is cooled to 30 ^oC?

  Options:
  A) 51.5
  B) 45.5
  C) 34.5
  D) 26.5
  Show Answer
  The correct answer is C .
• Question 80:

  At 25^o and zymase as catalyst,

  C₆H₁₂₆ → 2C₂H₅OH + 2CO₂ + energy

  The reaction above represented by the equation above is useful in the production of

  Options:
  A) propanol
  B) butanol
  C) methanol
  D) ethanol
  Show Answer
  The correct answer is D .