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 491:

  

  The diagram above represents an atom of

  Options:
  A) magnesium
  B) helium
  C) chlorine
  D) neon
  Show Answer
  The correct answer is A .
• Question 492: A molar solution of caustic soda is prepared by dissolving Options:
  A) 40 g NaOH in 100 g of water
  B) 40 g NaOH in 1000 g of water
  C) 20 g NaOH in 500 of solution
  D) 20 g NaOH in 1000 g of solution
  E) 2o g NaOH in 80 g of solution
  Show Answer
  The correct answer is B .
• Question 493: How many moles of (H+) are there in 1 dm³ of 0.5 M solution of H₂SO₄? Options:
  A) 2.0 moles
  B) 1.0 moles
  C) 0.5 mole
  D) 0.25 mole
  Show Answer
  The correct answer is B .
• Question 494:

  What volume of gas is evolved at S.t.p if 2g of calcium trioxocarbonate (IV) is added to a solution of hydrochloric acid?

  [Ca = 40, C = 12, O = 16, Cl = 35.5, H = 1 Molar volume of agas at s.t.p = 22.4 dm³

  Options:
  A) 112 cm²
  B) 224 cm²
  C) 448 cm²
  D) 2240 cm²
  Show Answer
  The correct answer is C .
• Question 495:

  A compound contains 40.0% carbon 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180, find the molecular formula.

  [H = 1, C = 12, O = 16]

  Options:
  A) CH₂O
  B) C₃H₆O₃
  C) C₆H₁₂O₆
  D) C₆H₁₂O₃
  Show Answer
  The correct answer is C .
• Question 496: When sodium ethanoate is treated with a few drops of concentrated tetraoxosulphate(vi)acid. one of the products is Options:
  A) CH₃COOH
  B) CH₃COOCH₃
  C) CH₃COOC₂H₅
  D) C₂H₅COOCH₃
  Show Answer
  The correct answer is A .
• Question 497:

  An organic compound which decolorizes bromine water is likely to be?

  Options:
  A) C${}_3$H${}_8$
  B) C${}_2$H${}_6$
  C) C${}_4$H${}_{1}0$
  D) C${}_2$H${}_4$
  Show Answer
  The correct answer is D .
• Question 498: The elements that belong to the third period of periodic table are Options:
  A) Li, Be, Al and D
  B) Na, P, O and Cl
  C) B, C, N, and O
  D) N2, Mg, S and Ar
  Show Answer
  The correct answer is D .
• Question 499:

  What quantity of electricity will liberate 0.125 mole of oxygen molecules during the electrolysis of dilute sodium chloride solution?

  [ F = 96 5000 C mol^-1 ]

  Options:
  A) 24 125 coulombs
  B) 48 250 coulombs
  C) 72 375 coulombs
  D) 96 500 coulombs
  Show Answer
  The correct answer is B .
• Question 500: The residual solids from the fractional distillation of petroleum are used as Options:
  A) coatings of pipes
  B) raw materials for the cracking process
  C) fuel for the driving tractors
  D) fuel for jet engines
  Show Answer
  The correct answer is A .