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 921: The type of iron that is best suited for welding, making nails, chains and iron rods is Options:
  A) pig iron
  B) wrought iron
  C) cast iron
  D) iron pyrites
  Show Answer
  The correct answer is B .
• Question 922:

  SO${}_3$ is not directly dissolved in water in the industrial preparation of H${}_2$SO${}_4$ by the contact process because

  Options:
  A) SO${}_3$ is an acidic gas
  B) Acid is usually added to water and not water to acid
  C) The reaction between SO${}_3$ and water is violently exothermic
  D) SO${}_3$ does not dissolve readily in water
  Show Answer
  The correct answer is C .
• Question 923: Two elements, P and Q with atomic numbers 11 and 8 respectively , combine chemically to form the compound P_xQ_Y. The respective values of x and y are? Options:
  A) 1 and 1
  B) 1 and 2
  C) 2 and 1
  D) 3 and 1
  Show Answer
  The correct answer is C .
• Question 924: Which of the following substance is a mixture? Options:
  A) Granulated sugar
  B) Sea-water
  C) Sodium chloride
  D) Iron fillings
  Show Answer
  The correct answer is B .
• Question 925: The solubility, in moles per dm³ of 20.2 g of potassium trioxonitrate (V) dissolve in 100 g of the resulting mixture is?(K = 39, O = 16, N =14). Options:
  A) 0.10
  B) 0.20
  C) 1.00
  D) 2.00
  Show Answer
  The correct answer is D .
• Question 926: The industrial preparation of hydrogen gas from water gas is referred to as Options:
  A) Bosch process
  B) Contact process
  C) Haber process
  D) Bayer Process
  Show Answer
  The correct answer is A .
• Question 927: What is the oxidation number of Z in K₃ZCl₆? Options:
  A) -3
  B) +3
  C) -6
  D) +6
  Show Answer
  The correct answer is B .
• Question 928: When a current I was passed through an electrolyte solution for 40 minutes, a mass X g of a univalent metal was deposited at the cathode. What mass of the metal will be deposited when a current 2I is passed through the solution for 10 minutes? Options:
  A) X/4 g
  B) X/2 g
  C) 2X g
  D) 4X g
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  The correct answer is B .
• Question 929: In the chemical reaction A + B $\to$ C + D, more of D is formed? Options:
  A) if the concentrated of A is reduced
  B) if the concentrated of B is reduced
  C) if the concentrated of C is reduced
  D) if the concentration of C is increased
  E) if D is continuously removed from the reaction mixture
  Show Answer
  The correct answer is E .
• Question 930: Which of the following statement is true of the electrochemical series? Options:
  A) Electropositivity of metals increase down the series
  B) Electropositivity of non-metals decrease down the series
  C) Electronegativity of non-metals decrease down the series
  D) Electropositivity of metals decreases down the series
  Show Answer
  The correct answer is D .