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:

  Why is water often referred to as the "universal solvent"?

  Options:
  A) Water is the most abundant substance on Earth
  B) Water is essential for all living organisms.
  C) Water is involved in many chemical reactions
  D) Water can dissolve a wide variety of substances due to its polar nature
  Show Answer
  The correct answer is D .
• Question 252: An oxide XO₂ has a vapour density of 32. What is the atomic mass of X? Options:
  A) 20
  B) 32
  C) 14
  D) 12
  Show Answer
  The correct answer is B .
• Question 253: Steam changes the colour of anhydrous cobalt (ll) chloride from Options:
  A) white to red
  B) blue to white
  C) blue to pink
  D) white to blue
  Show Answer
  The correct answer is C .
• Question 254: Oxidation of concentrated hydrochloric acid with manganese (IV) oxide liberates a gas used in the? Options:
  A) manufacture of tooth pastes
  B) treatment of simple golitre
  C) vulcanization of rubber
  D) sterilization of water
  Show Answer
  The correct answer is D .
• Question 255: Which of the following is observed when a solution of iron (III) chloride is mixed with a solution of sodium hydroxide? Options:
  A) A gas is evolved
  B) A deep blue precipitate is formed
  C) The resultant solution turns green turns
  D) A brown precipitate is formed
  Show Answer
  The correct answer is D .
• Question 256:

  

  Which of the following is the correct order in the above diagram increasing boiling point, of the isomeric C₅H₁₂ compounds?

  Options:
  A) A
  B) B
  C) C
  D) D
  E) E
  Show Answer
  The correct answer is A .
• Question 257: Which of the following is a property of ionic chlorides? Options:
  A) They can be decomposed by heat
  B) They react with aqueous AgNO₃ to give a white precipiate which is soluble in excess ammonia
  C) They explode when in contact with dry ammonia
  D) They react with concentrated tetraoxosulphate (IV) acid to give white fumes of chlorine gas
  Show Answer
  The correct answer is B .
• Question 258: The enzyme used in the hydrolysis of starch to dextrin and maltose is Options:
  A) amylase
  B) diastatse
  C) invertase
  D) zymase
  Show Answer
  The correct answer is B .
• Question 259: A compound commonly used for sterilization and preservation of specimens and food is Options:
  A) ethanol
  B) benzene
  C) ether
  D) ammonia
  Show Answer
  The correct answer is A .
• Question 260: The catalyst used in the contact process for the manufacture of tetraoxosulphate (VI) acid is Options:
  A) manganes (IV) oxide
  B) manganese (ll) tetraoxosulphate (VI)
  C) vanadium (V) oxide
  D) iron metal
  Show Answer
  The correct answer is C .