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 761:

  220g of carbon dioxide contains ----- moles

  Options:
  A) 5
  B) 6
  C) 3
  D) 4
  Show Answer
  The correct answer is A .
• Question 762:

  If the molecular mass of tetraoxosulphate (VI) acid is 98, calculate its vapour density.

  Options:
  A) 196
  B) 49
  C) 106
  D) 82
  Show Answer
  The correct answer is B .
• Question 763: The Arrhenius equation expresses the relationship between the speed of a reaction and its Options:
  A) Molecular collision
  B) Heat of reaction
  C) Catalyst
  D) Activation energy
  Show Answer
  The correct answer is A .
• Question 764: The fuming of kettles is caused by the presence in the water of Options:
  A) calcium tetraoxosulphate (IV)
  B) calcium hydrogentrionocarbonate (IV)
  C) calcium hydroxide
  D) calcium trioxocarbonate (IV)
  Show Answer
  The correct answer is B .
• Question 765: Fermentation is the Options:
  A) breaking down of carbohydrate to glucose
  B) conversion of sugar to alcohol in the presence of yeast
  C) breaking down of sugar to carbohydrate
  D) conversion of alcohol to sugar in the presence of yeast
  Show Answer
  The correct answer is B .
• Question 766: The shapes of CO${}_2$, H${}_2$O and CH${}_4$ respectively are Options:
  A) bent, linear and tetrahedral
  B) bent, tetrahedral and linear
  C) linear, bent and tetrahedral
  D) tetrahedral, linear and bent
  Show Answer
  The correct answer is C .
• Question 767:

  The general formula of alkanones is

  Options:
  A) RCHO
  B) R${}_2$CO
  C) RCOOH
  D) RCOOR
  Show Answer
  The correct answer is B .
• Question 768: Which of the following samples will react fastest with dilute trioxonitrate (V) acid? Options:
  A) 5 g of lumps of CacO₃ at 25°C
  B) 5 g of powered CacO₃ at 25°
  C) 5 g of lumps of CaCO₃ at 50°C
  D) 5 g of powered CaCO₃ AT 50°C
  Show Answer
  The correct answer is D .
• Question 769: The partial pressure of oxygen in a sample of air is 452 mm Hg and the total pressure is 780 mm Hg. What is the mole fraction of oxygen? Options:
  A) 0.203
  B) 0.579
  C) 2.030
  D) 5.790
  Show Answer
  The correct answer is B .
• Question 770: On heating, under suitable conditions, 1 litres of monoatomic gas,X, combines with 1¹/₂ litres of an oxide, What is the formula of the oxide. Options:
  A) XO₃
  B) X₂O₃
  C) X₃O₂
  D) XO₂
  E) None of the above
  Show Answer
  The correct answer is B .