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 1721: An isotope has an atomic number of 17 and a mass number of 36. Which of the following gives the correct number of neutrons and protons in an atom of the isotope? Options:
  A) Neutrons 53, Protons 17
  B) Neutrons 17, Protons 36
  C) Neutrons 19, Protons 17
  D) Neutrons 36, Protons 17
  Show Answer
  The correct answer is C .
• Question 1722: A gas jar was inverted over burning yellow phosphorus floating over water in a beaker. After burning, the water level was found to rise in the gas jar. The water level rises because Options:
  A) pressure inside the gas jar is greater than pressure outside it
  B) the air in the gas jar had been used up by burning
  C) oxygen in the gas jar had been used up by burning
  D) nitrogen in the gas jar had been used up by burning
  E) the temperature in the jar had risen considerably
  Show Answer
  The correct answer is C .
• Question 1723: When a little brine was added to a metal nitrate a white precipitate was formed which first turned violet and then black on exposure to ai. The metal nitrate is therefore? Options:
  A) sodium nitrate
  B) mercuric nitrate
  C) lithium nitrate
  D) silver nitrate
  E) potassium nitrate
  Show Answer
  The correct answer is D .
• Question 1724: The rate of diffusion of a gas Y is twice that of Z If the relative molecular mass of Y is 64 and the two gases diffuse under the same conditions, find the relative molecular mass of Z Options:
  A) 32
  B) 4
  C) 8
  D) 16
  Show Answer
  The correct answer is D .
• Question 1725:

  16.55g of lead (ll) trioxonitrate (V) was dissolved in 100g of distilled water at 20^oC, calculate the solubility of the solute in moldm-³

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

  Options:
  A) 0.05 g
  B) 2.00 g
  C) 1.00 g
  D) none of the above
  Show Answer
  The correct answer is D .
• Question 1726: In an electrochemical cell, polarization is caused by Options:
  A) Oxygen
  B) Hydrogen
  C) Tetraoxosulphate(IV) acid
  D) Chlorine
  Show Answer
  The correct answer is B .
• Question 1727: The coloured nature of transition metal ions are associated with their partially filled Options:
  A) f- orbital
  B) s- orbital
  C) p-orbital
  D) d-orbital
  Show Answer
  The correct answer is D .
• Question 1728: In which of the following is the oxidation state of oxygen different from its value in water? Options:
  A) OH^-
  B) H₃O⁺
  C) O^-
  D) H₂O₂
  E) SO₂
  Show Answer
  The correct answer is D .
• Question 1729: Nuclear fission involves the splitting of a heavy element into two nuclei of Options:
  A) nearly equal masses with a relaese of energy and radiaton
  B) equal masses with a relaese of energy
  C) equal masses with a release of energy and radiation
  D) unequal masses without any relaese of energy
  Show Answer
  The correct answer is A .
• Question 1730: Which of the following is a neutralization reaction? Options:
  A) Addition of sodium chloride solution to potassium chloride solution
  B) Addition of trioxonitrate (V) acid (nitric acid) to distilled water
  C) Addition of trioxonitrate (V) acid (nitric acid) to tetraoxosulphate (IV) acid (sulphuric acid)
  D) Addition of trioxonitrate (V) acid (nitric acid) to potassium trioxonitrate (V) (potassium nitrate) solution
  E) Addition of trioxonitrate (V) acid (nitric acid) to potassium hydroxide solution
  Show Answer
  The correct answer is E .