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 571: The modern process of manufacturing steel for iron is by Options:
  A) treatment with acids
  B) oxidation
  C) blast reduction
  D) treatment with alkanal
  Show Answer
  The correct answer is C .
• Question 572:

  How long would it take to deposit 0.08g of copper from CuCl₂ solution by passing a current of 0.5A?

  [Cu = 64, F = 96500 C mol_-1]

  Options:
  A) 6 mins
  B) 8 mins
  C) 24 mins
  D) 48 mins
  Show Answer
  The correct answer is B .
• Question 573:

  Na₂CO₃ + 2HCI → 2NaCI + H₂O + CO₂. Using the above equation, what volume of carbondioxide, measured at s.t.p is liberated when 53g of sodium carbonate is dissolved in hydrochloric acid?

  (1 mole of gas occupies 22.4 dm³ at s.t.p)

  (Na = 23, C = 12, O = 16)

  Options:
  A) 44.8 dm³
  B) 11.2 dm³
  C) 100.1 dm³
  D) 3.0 dm³
  E) 22.4 dm³
  Show Answer
  The correct answer is B .
• Question 574: Oxyacetylene flame is used for iron-welding because it Options:
  A) Makes the iron metals solidify very quickly
  B) Combines with oxygen to give a pop sound
  C) Evolves a lot of heat when burnt
  D) Dissociates to produce carbon (IV) oxide and oxygen
  Show Answer
  The correct answer is C .
• Question 575: The main impurity in iron ore during the extraction of iron is Options:
  A) Silicon (IV) oxide
  B) Carbon (IV) oxide
  C) Calcium trioxosilicate
  D) Sulphur (II) oxide
  Show Answer
  The correct answer is A .
• Question 576: An elements X with relative atomic mass 16.2 contains two isotopes ¹⁶₈X with relative abundance of 90% and ^m₈X with relative abundance of 10%. The value of m is Options:
  A) 16
  B) 18
  C) 12
  D) 14
  Show Answer
  The correct answer is B .
• Question 577: A change in temperature of a saturated solution disturb the equilibrium between the Options:
  A) Dissolved solute and the solvent
  B) Solvent and undissolved solute
  C) Dissolved solute and undissolved solute
  D) Dissolved solute and the solution
  Show Answer
  The correct answer is C .
• Question 578: In the production of soap, concentrated sodium chloride solution is added to Options:
  A) Increase the solubility of soap
  B) Decrease the solubility of the soap
  C) Saponify the soap
  D) Emulsify the soap
  Show Answer
  The correct answer is B .
• Question 579:

  How many atoms are present in 6.0g of magnesium?

  [Mg = 24, N_A = 6.02 x 10²³ mol^-1]

  Options:
  A) 1.20 x 10²²
  B) 2.41 x 10²²
  C) 1.51 x 10²³
  D) 3.02 x 10²³
  Show Answer
  The correct answer is C .
• Question 580: The chlorinated alkane often used industrially to remove grease is Options:
  A) tetrachloromethane
  B) chloromethane
  C) trichloromethane
  D) dichlorometane
  Show Answer
  The correct answer is A .