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 1:

  If 10.5g of lead (II) trioxonitrate (V) is dissolved in 20cm³ of distilled water at 18^oC, the solubility of the solute in mol dm^-3 is

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

  Options:
  A) 1.60
  B) 5.25
  C) 16.00
  D) 525.00
  Show Answer
  The correct answer is A .
• Question 2: A given mass of gas occupies 2 dm³ at 300k. At what temperature will its volume be doubled keeping the pressure constant? Options:
  A) 400 k
  B) 480 k
  C) 550 k
  D) 600 k
  Show Answer
  The correct answer is D .
• Question 3: A hydrocarbon has an empirical formula CH and a vapour density of 39. Determine its molecular formula.[C = 12, H = 1] Options:
  A) C₂H₆
  B) C₃H₈
  C) C₃H₄
  D) C₆H₆
  Show Answer
  The correct answer is D .
• Question 4:

  Which of the following methods can be used to remove temporary hardness from water?

  Options:
  A) Boiling
  B) Filtration
  C) sedimentation
  D) Chlorination
  Show Answer
  The correct answer is A .
• Question 5: Temporary hard water is formed when rain water containing dissolved carbon(IV) oxide flows over deposits of Options:
  A) CaCO₃
  B) Na₂CO₃
  C) Na₂SO₄
  D) CaSO₄
  Show Answer
  The correct answer is A .
• Question 6: The shape of the hydrocarbon compound CH₄ is Options:
  A) square planar
  B) planar
  C) linear
  D) tetrahedral
  Show Answer
  The correct answer is D .
• Question 7:

  

  The IUPAC nomenclature of the organic compound with the above structural formula is

  Options:
  A) 3-ethyl-2,5-dimethylhexane
  B) 4-ethyl-2,5-dimethylhexane
  C) 3-ethyl-2,5,5 - trimethylpentane
  D) 3-ethyl, 1,1,4-trimethylpentane
  Show Answer
  The correct answer is A .
• Question 8:

  Which of the following is the best starting material for the preparation of oxygen? Heating of trioxonitrate (v) with

  Options:
  A) Pb
  B) Zn
  C) Ca
  D) Na
  Show Answer
  The correct answer is A .
• Question 9: The mathematical expression of PH is Options:
  A) log ₁₀[OH^-]
  B) log ₁₀1/[H ₃ O⁺]
  C) log ₁₀[H ₃ O⁺]
  D) log ₁₀1/[OH ^-]
  Show Answer
  The correct answer is B .
• Question 10:

  Na₂CO_3(g) + 2HCl_(aq) → 2NaCl_(aq) + H₂O_(l) + CO_2(g)

  How many moles of sodium trioxocarbonate (IV) are there in a 25 cm³ solution which required 10cm³ of 0.05 mol dm^-3 hydrochloric acid solution to neutralize it?

  Options:
  A) 1.000 mole
  B) 0.100 mole
  C) 0.010 mole`
  D) 0.111 mole
  Show Answer
  The correct answer is C .