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 251: The fraction of crude oil used as jet fuel is? Options:
  A) refinery gas
  B) diesel oil
  C) kerosene
  D) gasoline
  Show Answer
  The correct answer is C .
• Question 252: Moving from left to right across a period, the general rise in the first ionization energy can be attributed to the Options:
  A) decrease in nuclear charge
  B) increase in nuclear charge
  C) decrease in screening effect
  D) increase in screening effect
  Show Answer
  The correct answer is B .
• Question 253:

  

  In the diagram above, the gas produced is

  Options:
  A) NO
  B) NO₂
  C) N₂O
  D) N₂O₄
  Show Answer
  The correct answer is A .
• Question 254:

  In the extraction of iron, hot air is introduced into the blast furnacethrough?

  Options:
  A) valves
  B) open-hearths
  C) arcs
  D) tuyeres
  Show Answer
  The correct answer is D .
• Question 255: Which of the following samples will react fastest with dilute trioxonitrate (V) acid? Options:
  A) 5 g of lumps of CacO₃ at 25°C
  B) 5 g of powered CacO₃ at 25°
  C) 5 g of lumps of CaCO₃ at 50°C
  D) 5 g of powered CaCO₃ AT 50°C
  Show Answer
  The correct answer is D .
• Question 256: A side effect of soft water is that Options:
  A) it gives offensive taste
  B) excess calcium is precipitated
  C) it attacks lead contained in pipes
  D) it encourage the growth of bacteria
  Show Answer
  The correct answer is C .
• Question 257: The substance often use for vulcanization of rubber is Options:
  A) chlorine
  B) hydrogen peroxide
  C) sulphur
  D) tetraoxosulphate (IV) acid
  Show Answer
  The correct answer is C .
• Question 258:

  A mixture of iron and sulphur can be separated by dissolving the mixture in?

  Options:
  A) steam
  B) dilute hydrochloric acid
  C) dilute sodium hydroxide
  D) benzene
  Show Answer
  The correct answer is B .
• Question 259:

  When a substance is oxidized, it

  Options:
  A) Loses electrons
  B) Gains oxygen atoms
  C) Gains electrons
  D) Loses protons (H+ ions)
  Show Answer
  The correct answer is A .
• Question 260:

  Which of the following is a non-metal that remains liquid at room temperature?

  Options:
  A) Chlorine
  B) Phosphorus
  C) Bromine
  D) Helium
  Show Answer
  The correct answer is C .