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 551:

  Burning magnesium ribbon in air removes which of the following

  (i) oxygen (ii) nitrogen (iii) argon and (iv) carbon(iv)oxide?

  Options:
  A) i and iv only
  B) i, ii, iii and iv only
  C) i only
  D) i and ii only
  Show Answer
  The correct answer is C .
• Question 552:

  

  If in the graph above 1 dm³ of a saturated solution of KCL is cooled from 80^oC, the mass of crystals deposited will be  [K = 39, Cl = 35.5]

  Options:
  A) 7.45 g
  B) 14.90 g
  C) 74.50 g
  D) 149.00 g
  Show Answer
  The correct answer is D .
• Question 553: Na₂C₂O₄ + CaCl₂ → CaC₂O₄ + 2NaCl. Given a solution of 1.9g of sodium oxalate in 50g of water at room temperature, calculate the minimum volume of 0.1 M calcium oxalate using the above equation? Options:
  A) 1.40 χ 10² dm³
  B) 14.0 χ 10² cm³
  C) 1.40 χ 10^-2 dm^-2
  D) 14.0 χ 10^-2 cm³
  Show Answer
  The correct answer is A .
• Question 554: The normal boiling point of a liquid is defined as Options:
  A) the temperature at which its vapour pressure equals the atmospheric pressure
  B) the temperature at which bubbles begin to form
  C) the temperature at which the vapour pressure equals 1 temperature
  D) the temperature at which the rate of condensation of vapour equals the rate of vaporisation of the liquid
  E) the temperature at which the space above the liquid is saturated
  Show Answer
  The correct answer is C .
• Question 555: The relatively high boiling points of alkanols are due to? Options:
  A) ionic bonding
  B) aromatic character
  C) covalent bonding
  D) hydrogen bonding
  Show Answer
  The correct answer is D .
• Question 556: Unsaturated organic compounds are identified by decolourization of Options:
  A) silver bromine and potassium tetraoxomanganate (VII) solutions
  B) bromine water and acidified potassium tetraoxomanganate (VII) solution
  C) silver bromide solution and bromine water
  D) bromine water and alkaline potassium tetraoxomanganate (VII) solution
  Show Answer
  The correct answer is B .
• Question 557:

  Which separation technique is used to separate different pigments in a mixture based on their affinity for a stationary phase and a mobile phase?

  Options:
  A) Chromatography
  B) Filtration
  C) Decantation
  D) Distillation
  Show Answer
  The correct answer is A .
• Question 558: One mole of a hydrocarbon contains 36g of carbon and its vapour density is 20. The structure of the hydrocarbon is Options:
  A) CH₃C ≡ CH
  B) CH₃CH = CH₂
  C) CH₃CH₂C ≡ CH
  D) CH₃CH₂ CH₃
  Show Answer
  The correct answer is A .
• Question 559:

  200 cm³ of air was passed over heated copper in a syringe several times to produce copper (II) oxide.

  When cooled, the final volume of air recorded was 158cm³. Estimate the percentage of oxygen in the air?

  Options:
  A) 31%
  B) 27%
  C) 21%
  D) 19%
  Show Answer
  The correct answer is C .
• Question 560: For a general equation of the nature xP + yQ → mR + nS, the expression for the equilibrium constant is Options:
  A) k [P]^x [Q]^y
  B) $\frac{[P{]}^x[Q{]}^y}{[R{]}^m[S{]}^n}$
  C) $\frac{[R{]}^m[S{]}^n}{[P{]}^x[Q{]}^y}$
  D) $\frac{m[R]n[S]}{x[P]y[Q]}$
  Show Answer
  The correct answer is C .