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 861: Carbohydrates are large molecules with the molecular formula C _x (H₂O)_y. In which of the following pairs is x not equal to y? Options:
  A) glucose and starch
  B) maltose and starch
  C) sucrose and fructose
  D) maltose and starch
  Show Answer
  The correct answer is A .
• Question 862:

  The following compounds are given with their corresponding boiling points.

  Compound Boiling Point

  i.................................14°C

  ii................................24°C

  iii................................0°C

  iv................................120°C

  V.................................-2°C

  From the above information, indicate which of the following is correct?

  Options:
  A) All the compounds are gaseous at 20 °C
  B) One of the compounds is gaseous at 20 °C
  C) Two of the compounds are gaseous at 20 °C
  D) Three of the compounds are gaseous at 20 °C
  E) None of the compounds is gaseous at 20 °C
  Show Answer
  The correct answer is D .
• Question 863: An oxide XO₂ has a vapour density of 32. What is the atomic mass of X? Options:
  A) 32
  B) 20
  C) 14
  D) 12
  Show Answer
  The correct answer is A .
• Question 864:

  Which of the following metals is the most essential in the regulation of blood volume, blood pressure and osmotic equilibrium?

  Options:
  A) Zinc
  B) Manganese
  C) Sodium
  D) Iron
  Show Answer
  The correct answer is C .
• Question 865: A gas that can behave as a reducing agent towards chlorine and as an oxidizing agent toward hydrogen sulphide is Options:
  A) O₂
  B) NO
  C) SO₂
  D) NH₃
  E) CO₂
  Show Answer
  The correct answer is C .
• Question 866:

  

  Use the table above to answer this question .The least reactive element is

  Options:
  A) W
  B) X
  C) Y
  D) Z
  Show Answer
  The correct answer is D .
• Question 867:

  The mass number of a nucleus is?

  Options:
  A) Always less than its atomic number
  B) The sum of the number of protons and neutrons present in the nucleus
  C) Always more than the atomic weight
  D) A fraction
  Show Answer
  The correct answer is B .
• Question 868: The oxidation state of oxygen in tetraoxosulphate (VI) acid is Options:
  A) -4
  B) -2
  C) +4
  D) -8
  Show Answer
  The correct answer is B .
• Question 869: 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 870: Which of the additives could improve the quality of steel? Options:
  A) Silicon
  B) Sulphur and phosphorus
  C) Carbon
  D) Chromium and nickel
  Show Answer
  The correct answer is D .