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 161:

  

  The diagram above is the solubility curve of a solute, X. Find the amount of X deposited when 500cm³ of a solution of X is cooled from 60^oC to 20^oC.

  Options:
  A) 0.750 mole
  B) 0.950 mole
  C) 2.375 moles
  D) 4.750 moles
  Show Answer
  The correct answer is A .
• Question 162:

  When dilute aqueous solutions of lead (II) nitrate and potassium bromide are mixed, a precipitate is observed.

  The products of this reaction are?

  Options:
  A) PbO_(s) + Br^- + KNO₃
  B) Br₂ + NO_2(g) + PbBr_2(s)
  C) PbO_(s) + K⁺_(aq) + Br_(aq) + NO_2(g)
  D) PbBr_2(s) + K_(aq) + K⁺_(aq) + NO_3(aq)
  Show Answer
  The correct answer is D .
• Question 163: Which of the following hydrogen halides the highest entropy value? Options:
  A) HF
  B) HCl
  C) HBr
  D) HI
  Show Answer
  The correct answer is A .
• Question 164: The nitrogen obtained from air has a density higher than the one from nitrogen-containing compounds because the one from air is contaminated with Options:
  A) water vapour
  B) oxgyen
  C) rare gases
  D) carbon (IV) oxide
  Show Answer
  The correct answer is C .
• Question 165: Hydrogen can be displaced from a lot alkaline solution by Options:
  A) Fe
  B) Cu
  C) Cn
  D) Sn
  Show Answer
  The correct answer is A .
• Question 166: What weight of sodium hydroxide is required to make 500 cm³ of 0.2 M solution?(Na = 23, O = 16, H = 1) Options:
  A) 40 g
  B) 20 g
  C) 10 g
  D) 4 g
  E) 2 g
  Show Answer
  The correct answer is D .
• Question 167: Which of the gases is employed as an anaesthesia? Options:
  A) N ₂O
  B) NO₂
  C) NH₃
  D) NO
  Show Answer
  The correct answer is A .
• Question 168:

  The conductivity of an acid solution depends on the

  Options:
  A) amount of ions present and their mobilities
  B) mobilities of the ions present
  C) amount of ions present
  D) temperature of the solution
  Show Answer
  The correct answer is A .
• Question 169: The boiling point of water is higher than that of methanol because? Options:
  A) water is oxide while methanol is an alcohol
  B) inter molecular forces in water are stronger than those in methanol
  C) water is an inorganic compound while methanol is organic
  D) water is an ionic compound while methanol is a covalent compound
  E) water is more reactive than methanol
  Show Answer
  The correct answer is B .
• Question 170: Copper (II) tetraoxosulphate (VI) solution is electrolyzed using carbon electrodes. Which of the following are produced at the anode and cathode respectively ? Options:
  A) Copper and oxygen
  B) Oxygen and copper
  C) Hydrogen and copper
  D) Copper and hydrogen
  Show Answer
  The correct answer is B .