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 21:

  Elements P, Q, R, S have 6, 11, 15, 17 electrons respectively, therefore,

  Options:
  A) P will form an electrovalent bond with R
  B) Q will form a covalent bond with S
  C) R will form an electrovalent bond with S
  D) Q will form an electrovalent bond with S
  E) Q will form a covalent bond with R
  Show Answer
  The correct answer is D .
• Question 22: The Arrhenius equation expresses the relationship between the speed of a reaction and its Options:
  A) Molecular collision
  B) Heat of reaction
  C) Catalyst
  D) Activation energy
  Show Answer
  The correct answer is A .
• Question 23:

  In the preparation of oxygen by heating KCIO, in the presence of MnO${}_2$ only moderate heat is needed because the catalyst acts by ${}_2$

  Options:
  A) lowering the pressure of the reaction
  B) increasing the surface area of the reaction
  C) increasing the rate of the reaction
  D) lowering the energy barrier of the reaction
  Show Answer
  The correct answer is D .
• Question 24:

  Which of the following pairs of substances will react further with oxygen to form a higher oxide?

  Options:
  A) CO${}_2$ and H${}_2$O
  B) NO and H${}_2$O
  C) CO and CO${}_2$
  D) SO${}_2$ and NO
  Show Answer
  The correct answer is D .
• Question 25: The temperature of a body decreases when drops of liquid placed on it evaporate because? Options:
  A) the atmospheric vapour pressure has a cooling effect on the body
  B) a temperature gradient exists between the drops of liquid and the body causing the latter to vaporate
  C) the heat of vapourization is drawn from the body causing it to cool
  D) the random motion of the liquid molecules causes a cooling effect on the body
  Show Answer
  The correct answer is C .
• Question 26: The property which makes alcohol soluble in water is the Options:
  A) boiling point
  B) hydrogen bonding
  C) ionic character
  D) covalent nature
  Show Answer
  The correct answer is B .
• Question 27:

  

  In the above set up substances X and Y are respectively

  Options:
  A) lime water copper (ll) tetraoxosulphate (lV)
  B) potassium trioxocarbonate and alkaline pyrogallol
  C) potassium hydroxide and alkaline pyrogallol
  D) potassium trioxocarbonate (lV) and concentrated tetraoxosulphate (IV) acid
  Show Answer
  The correct answer is C .
• Question 28: The colour of litmus in an alkaline medium is Options:
  A) Red
  B) Yellow
  C) Pink
  D) Blue
  Show Answer
  The correct answer is D .
• Question 29: One of the products of the thermal decomposition of sodium trioxonitrate (V) is Options:
  A) sodium
  B) nitrogen
  C) sodium dioxonitrate (III)
  D) sodium oxide
  Show Answer
  The correct answer is C .
• Question 30: A polymerization reaction is one in which? Options:
  A) small molecules form giant molecules
  B) atoms form molecules
  C) giant molecules form small molecules
  D) molecules form volatile compounds
  E) a molecule rearranges itself
  Show Answer
  The correct answer is A .