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 61:

  200cm³ each of 0.1M solutions of lead (II) trioxonitrate (V) and hydrochloric acid were mixed. Assuming that lead (II) chloride is completely insoluble, calculate the mass of lead (II) chloride that will be precipitated.

  [Pb = 207, Cl= 35.5, N = 14, O = 16]

  Options:
  A) 2.78g
  B) 5.56g
  C) 8.34g
  D) 11.12g
  Show Answer
  The correct answer is B .
• Question 62:

  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 63:

  The solubility in mol dm^-3 of 20g of CuSO₄ dissolved in 100g of water at 180^o is

  [Cu = 64, S = 32, O =16]

  Options:
  A) 0.13
  B) 0.25
  C) 1.25
  D) 2.00
  Show Answer
  The correct answer is C .
• Question 64:

  How many alkoxyalkanes can be obtained from the molecular formula C${}_4$H${}_{10}$O?

  Options:
  A) 4
  B) 2
  C) 1
  D) 3
  Show Answer
  The correct answer is D .
• Question 65: Which of the following pairs has compounds that are isomers? Options:
  A) Propanal and propanone
  B) Ethanoic acid and ethylmethanoate
  C) Ethanoic acid and ethane-1, 2-diol
  D) 2-methylbutane and 2, 2-dimethylbutane
  Show Answer
  The correct answer is D .
• Question 66:

  Wrought iron is obtained by heating cast iron in a furnace with?

  Options:
  A) magnetite
  B) haematite
  C) carbon(ii)oxide
  D) calcium trioxosilicate(iv)
  Show Answer
  The correct answer is B .
• Question 67:

  What is the maximum number of electrons that can occupy the second energy level (n=2)?

  Options:
  A) 2 electrons
  B) 18 electrons
  C) 8 electrons
  D) 32 electrons
  Show Answer
  The correct answer is C .
• Question 68:

  If 30cm³ of oxygen diffuses through a porous pot in 7 seconds, how long will it take 60cm³ of chlorine to diffuse through the same pot, if the vapour densities of oxygen and chlorine are 16 and 36 respectively?

  Options:
  A) 9.3 sec
  B) 14 sec
  C) 21 sec
  D) 28 sec
  E) 30.3 sec
  Show Answer
  The correct answer is C .
• Question 69: The colour changes observed when testing for reducing agents using acidified potassium heptaoxodichromate (IV) solution is Options:
  A) yellow to purple
  B) orange to green
  C) green to orange
  D) purple to yellow
  Show Answer
  The correct answer is B .
• Question 70:

  When ammonia and hydrogen ion bond together to form ammonium ion, the bond formed is called

  Options:
  A) electrovalent bond
  B) co-ordinate bond
  C) ionic bond
  D) covalent bond
  Show Answer
  The correct answer is B .