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 1731: 0.25 mole of hydrogen chloride was dissolved in distilled water and the volume made up of 0.50 dm³. If 15.0 cm³ of the solution requires 12.50 cm³ of aqueous sodium trioxocarbonate (IV) for neutralization, calculate the concentration of the alkaline solution Options:
  A) 0.30 mol dm³
  B) 0.40 mol dm³
  C) 0.50 mol dm³
  D) 0.60 mol dm³
  Show Answer
  The correct answer is A .
• Question 1732: A few drops of concentrated HNO₃ is added to an unknown solution and boiled for a while. If this produces a brown solution, the cation presents is likely to be Options:
  A) Pb²⁺
  B) Cu²⁺
  C) Fe³⁺
  D) Fe²⁺
  Show Answer
  The correct answer is D .
• Question 1733: The gas formed when ammonium trioxonitrate (V) is heated with sodium hydroxide is? Options:
  A) hydrogen
  B) nitrogen (IV) oxide
  C) oxygen
  D) ammonium
  Show Answer
  The correct answer is D .
• Question 1734: The reddish-brown rust on iron roofing sheets consists of Options:
  A) Fe³⁺(H₂O)₆
  B) FeO.H₂O
  C) Fe₂O₃.3H₂O
  D) Fe₃O₄.2H₂O
  Show Answer
  The correct answer is C .
• Question 1735: In the electrolytic extraction of aluminum, the function of the molten cryolite is to Options:
  A) precipitate aluminium hdroxide
  B) lower the melting point of aluminium oxide
  C) act as a raw materials
  D) act as a solvent
  Show Answer
  The correct answer is B .
• Question 1736: Which one of the following metals is not normally extracted by chemical reduction because of its position in the electrochemical series? Options:
  A) Copper
  B) Iron
  C) Lead
  D) Potassium
  E) Zinc
  Show Answer
  The correct answer is D .
• Question 1737: Phosphorus burns in oxygen according to the equation P₄ + 50₂ → P₄O₁₀. How many litres of oxygen will be required at S.T.P for complete oxidation of 12.4g of phosphorus? [P = 31,O = 16 and molar volume of a gas at S.T.P = 22.4 litres] Options:
  A) 5. 20
  B) 11. 20
  C) 2. 24
  D) 20. 20
  E) 6. 20
  Show Answer
  The correct answer is B .
• Question 1738: Iron is often galvanized in order to Options:
  A) Make it more malleable
  B) Remove the impurities unit
  C) Protect it against corrosion
  D) Render it passive
  Show Answer
  The correct answer is C .
• Question 1739: Which of the following is arranged in order of increasing electronegativity? Options:
  A) Chlorine, aluminium, magnesium, phosphorus, sodium
  B) sodium, magnesium, aluminium, phosphorus, chlorine
  C) Chlorine, phosphorus, phosphorous, aluminium, magnesium, sodium
  D) Sodium, chlorine, phosphorus, magnesium, aluminium
  Show Answer
  The correct answer is B .
• Question 1740: What volume of 0.5mldm³ H₂SO₄ will exactly neutralize 20cm³ of 0.1moldm³ NaOH Solution? Options:
  A) 2.0cm³
  B) 5.0cm³
  C) 6.8cm³
  D) 8.3cm³
  Show Answer
  The correct answer is A .