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 211:

  An organic compound has an empirical formula CH₂O and vapour density of 45.

  What is the molecular formula?

  [C = 12, H = 1, O = 16]

  Options:
  A) C₃H₇OH
  B) C₂H₅OH
  C) C₃H₆O₃
  D) C₂H₄O₂
  Show Answer
  The correct answer is C .
• Question 212: What is the decrease in volume of air when pyrogallol is shaken with 30.00cm³ of air ? Options:
  A) 15.00cm³
  B) 6.30cm³
  C) 0.63cm³
  D) 0.06cm³
  Show Answer
  The correct answer is B .
• Question 213: One of the products of the thermal decomposition of sodium trioxonitrate (V) is Options:
  A) sodium
  B) nitrogen
  C) sodium dioxonitrate (III)
  D) sodium oxide
  Show Answer
  The correct answer is C .
• Question 214: Which of the following pollutants is associated with brain damage? Options:
  A) Carbon (ll) oxide
  B) Radioactive fallout
  C) Biodegradable waste
  D) Sulphus (lV) oxide
  Show Answer
  The correct answer is A .
• Question 215:

  

  The compound above is the product of the oxidation of

  Options:
  A) 2-methlbutan-2-ol
  B) 2-methylbutan -1- ol
  C) 2, 3-dimethylprop 1-ol
  D) Pentan -2- ol
  Show Answer
  The correct answer is B .
• Question 216:

  What is the symbol used to represent an alpha particle?

  Options:
  A) α
  B) γ
  C) δ
  D) β
  Show Answer
  The correct answer is A .
• Question 217:

  How many grams of H₂SO₄ are necessary for the preparation of 0.175 dm³ of M 6.00 M H₂SO₄?

  (S = 32.06, O = 16.00 H = 1.00)

  Options:
  A) 206.0 g
  B) 103.0 g
  C) 98.1 g
  D) 51.5 g
  Show Answer
  The correct answer is B .
• Question 218: The alkyl group is represented by the general formula Options:
  A) C_nH₂n
  B) C_nH₂n − 2
  C) C_nH₂n + 1
  D) C_nH₂n + 2
  Show Answer
  The correct answer is C .
• Question 219:

  I. It has a varied composition from one place to another.

  II. It constituents can be separated by physical means.

  III. It contains unreactive noble gases

  Which of the above shows that air is a mixture?

  Options:
  A) I and II only
  B) II and III only
  C) I and III only
  D) I, II and III
  Show Answer
  The correct answer is A .
• Question 220: The constituent of air necessary in the rusting process are Options:
  A) O₂ and H₂O
  B) Ar and CO₂
  C) CO₂ and H₂O
  D) O₂ and CO₂
  Show Answer
  The correct answer is D .