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 721: The general formula of an alkyl halide (where X represents the halide) is? Options:
  A) C_nH_2n2X
  B) C_nH_2n + ₁X
  C) C_nH_2n + ₂X
  D) C_nH_2nX
  Show Answer
  The correct answer is B .
• Question 722: Which of the following happens during the electrolysis of molten sodium chloride? Options:
  A) Sodium ion loses an electron
  B) Chlorine atom gains an electron
  C) Chlorine ion gains an electron
  D) Sodium ion is oxidized
  E) Chloride ion is oxidized
  Show Answer
  The correct answer is E .
• Question 723: Hydrogen can be displaced from a lot alkaline solution by Options:
  A) Fe
  B) Cu
  C) Cn
  D) Sn
  Show Answer
  The correct answer is A .
• Question 724:

  What mass of K₂CrO₄ is required to prepare 250cm³ of 0.020 mol dm³ solution?

  [K₂CrO₄ = 194.2g mol^-1]

  Options:
  A) 0.97g
  B) 9.70g
  C) 19.42g
  D) 97.10g
  Show Answer
  The correct answer is A .
• Question 725: Smog usually occurs over cities which Options:
  A) burn a lot of fossil fuels
  B) have very few plants
  C) are surrounded by water
  D) are overpopulated
  Show Answer
  The correct answer is A .
• Question 726: The air around smelting industries is likely to contain Options:
  A) H₂S, CO and N₂
  B) CO₂, SO₃ and H₂
  C) H₂, SO₂ and CO₂
  D) SO₂, N₂ and CO₂
  Show Answer
  The correct answer is C .
• Question 727: the vapour density of a gas may be defined as Options:
  A) the mass of a unit volume of the gas compared to an equal volume of water vapour
  B) the mass of a unit volume of the gas compared to an equal volume of hydrogen
  C) the mass of a unit volume of the gas compared to an equal volume of oxygen
  D) the mass of a unit volume of the gas minus the vapour pressure of water
  E) two times the relative molecular mass of the gas
  Show Answer
  The correct answer is B .
• Question 728:

  What current will deposit 3.25g of zinc in 2hrs?

  [Zn = 65, F = 96500 mol^-]

  Options:
  A) 3.25A
  B) 2.00A
  C) 1.34A
  D) 0.67A
  Show Answer
  The correct answer is C .
• Question 729: The purest from of iron which contains only about 0.1% carbon is Options:
  A) pig iron
  B) wrough iron
  C) cast iron
  D) iron pyrite
  Show Answer
  The correct answer is B .
• Question 730: In the industrial production of H₂ is removed by (solution) Options:
  A) washing under pressure
  B) drying over phosphorus (V) oxide
  C) passing the mixture to the limewater
  D) using ammonical copper (I) chlorine
  Show Answer
  The correct answer is A .