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 71: One mole of hydrocarbon contains 6g of hydrogen. If the molecular weight is 54, the hydrocarbon is an? Options:
  A) alkanone
  B) alkane
  C) alkene
  D) alkyne
  Show Answer
  The correct answer is D .
• Question 72: Which of the following gases may not be dried with concentrated sulphuric acid? Options:
  A) HCl
  B) N₂
  C) Cl₂
  D) SO₂
  E) NH₃
  Show Answer
  The correct answer is E .
• Question 73: A chemical reaction is always associated with Options:
  A) an increase in the composition of one of the substance
  B) a change in the volume of the reactants
  C) a change in the nature of the reactants
  D) the formation of new substance
  Show Answer
  The correct answer is D .
• Question 74: When H₂S is passed into a solution of iron (III) chloride, the solution turns Options:
  A) Pale green
  B) Pale red
  C) Brown
  D) Colourless
  Show Answer
  The correct answer is A .
• Question 75:

  At room temperature and standard pressure, chlorine gas is in which state of matter?

  Options:
  A) Plasma
  B) Solid
  C) Liquid
  D) Gas
  Show Answer
  The correct answer is D .
• Question 76: How many grams of bromine will be required to completely react with 10 g of propyne?(C = 12, H = 1, Br = 80) Options:
  A) 20 g
  B) 40 g
  C) 60 g
  D) 80 g
  Show Answer
  The correct answer is D .
• Question 77: Which of the following statements is incorrect? Options:
  A) Calcium reacts with water to form calcium
  B) Magnesium reacts very slowly with water but faster with warm water
  C) Iron will not react with water in the absence of air
  D) Sodium reacts with water
  E) Copper reacts with steam
  Show Answer
  The correct answer is E .
• Question 78: A metal X forms two bromides with the formulae XBr₂ and XBr₃. What type of bonding exists between X and bromine in the bromide? Options:
  A) Ionic bonding
  B) Metallic bonding
  C) Dative bonding
  D) Covalent bonding
  Show Answer
  The correct answer is A .
• Question 79: The solubility product of Cu(IO₃)₂ is 1.08 * 10^-7. Assuming that neither ions react appreciable with water to form H⁺ and OH^-, what is the solubility of this salt? Options:
  A) 2.7 * 10^-8 mol dm^-3
  B) 9.0 * 10^-8 mol dm^-3
  C) 3.0 * 10^-3 mol dm^-3
  D) 9.0 * 10^-3 mol dm^-3
  Show Answer
  The correct answer is D .
• Question 80: A compound contains 40.0% C, 6.7% H 53.3% O. If the molecular mass of the compound is 180, its molecular formula is [C =12, H =1,O] Options:
  A) CH₂O
  B) C₃H₆O₃
  C) C₆H₆O₃
  D) C₆H₁₂O₆
  Show Answer
  The correct answer is D .