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 611: What reaction takes place when palm-oil is added to potash and foam are observed? Options:
  A) Neutralization
  B) Saponification
  C) Esterification
  D) Salting-out
  Show Answer
  The correct answer is B .
• Question 612: When chlorine is passed into water and subsequently exposed to sunlight, the gas evolved is? Options:
  A) HCl
  B) HOCl
  C) O₂
  D) Cl₂O
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  The correct answer is C .
• Question 613: Which of the following statements is FALSE about isotopes of the same element? Options:
  A) They have the same number of electrons in their outermost shells
  B) They have different atomic masses
  C) They have the same atomic number and the number of electrons
  D) They have the same atomic number but different umber of elelctrons
  Show Answer
  The correct answer is D .
• Question 614:

  The sulphide that is commonly used in coating electric fluorescent tubes is?

  Options:
  A) iron(ii)Sulphide
  B) tin(ii)sulphide
  C) Zinc Sulphide
  D) lead(iv) Sulphide
  Show Answer
  The correct answer is C .
• Question 615: Which of the noble gases has the greatest ionization energy Options:
  A) He
  B) Xe
  C) Ar
  D) Rr
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  The correct answer is A .
• Question 616:

  56.00cm³ of a gas at S.T.P. weighed 0.11g. What is the vapour density of the gas?
  [Molar volume of a gas at S.T.P = 22.4dm³]

  Options:
  A) 11.00
  B) 22.00
  C) 33.00
  D) 44.00
  Show Answer
  The correct answer is B .
• Question 617: The volume occupies by 1.58g of a gas at s.t.p is 500cm³. What is the relative molecular mass of the gas? (G.M.V at s.t.p = 22.40dm³) Options:
  A) 28
  B) 32
  C) 44
  D) 71
  Show Answer
  The correct answer is D .
• Question 618:

  How long would it take to deposit 0.08g of copper from CuCl₂ solution by passing a current of 0.5A?

  [Cu = 64, F = 96500 C mol_-1]

  Options:
  A) 6 mins
  B) 8 mins
  C) 24 mins
  D) 48 mins
  Show Answer
  The correct answer is B .
• Question 619: Oxygen-demanding waste are considered to be a water pollutant because they? Options:
  A) deplete oxygen which is necessary for the survival of aquatic organism
  B) increase oxygen which is necessary for survival of aquatic organism
  C) increase other gaseous substances which are necessary for the survival of aquatic organisms
  D) deplete other gaseous species which is necessary for the survival of aquatic organisms
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  The correct answer is A .
• Question 620: If 100cm³ of oxygen pass through a porous plug is 50 seconds, the time taken for the same volume of hydrogen to pass through the same porous plug is? [O = 16, H = 1] Options:
  A) 10.0s
  B) 12.5s
  C) 17.7s
  D) 32.0s
  Show Answer
  The correct answer is B .