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 31: Which of the following decreases when a given mass of gas is compressed to half its initial volume? Options:
  A) Average intermolecular distance
  B) Frequency of collisions
  C) Number of molecules present
  D) Atomic radius of each particle
  Show Answer
  The correct answer is A .
• Question 32:

  What is the molar mass of water (H2O)?

  Options:
  A) 18 g/mol
  B) 22 g/mol
  C) 16 g/mol
  D) 12 g/mol
  Show Answer
  The correct answer is A .
• Question 33:

  Aluminum hydroxide is used in the dyeing industry as a?

  Options:
  A) Dye
  B) Dispersant
  C) Salt
  D) Mordant
  Show Answer
  The correct answer is D .
• Question 34: The characteristics reaction of carbonyl compounds is? Options:
  A) substitution
  B) elimination
  C) addition
  D) saponfication
  Show Answer
  The correct answer is C .
• Question 35:

  What is the molecular geometry of a molecule with three bonding pairs and no lone pairs around the central atom?

  Options:
  A) Tetrahedral
  B) Trigonal planar
  C) Linear
  D) Octahedral
  Show Answer
  The correct answer is B .
• Question 36: A sample of orange juice is found to have a PH of 3.80. What is the concentration of the hydroxide ion in the juice? Options:
  A) 1.6 $\times$ 10^-4
  B) 6.3 $\times$ 10^-11
  C) 6.3 $\times$ 10^-4
  D) 1.6 $\times$ 10^-11
  Show Answer
  The correct answer is B .
• Question 37: Vulcanization of rubber is a process by which Options:
  A) isoprene units are joined to produce rubber
  B) rubber latex is coagulated
  C) sulphur is chemically combined in the rubber
  D) water is removed from the rubber
  Show Answer
  The correct answer is C .
• Question 38: Which of the following solutions will conduct the least amount of electricity? Options:
  A) 2.00 M aqueous solution of NaOH
  B) 0.01 M aqueous solution of NaOH
  C) 0.01 M aqueous solution of hexanoic acid
  D) 0.01 M aqueous solution of sugar
  Show Answer
  The correct answer is D .
• Question 39: The densities of two gases, X and Y are 0.5gdm^-3 and 2.0gdm^-3 respectively. What is the rate of diffusion of X relative to Y? Options:
  A) 0.1
  B) 0.5
  C) 2.0
  D) 4.0
  Show Answer
  The correct answer is C .
• Question 40: Helium is often used in observation balloons because it is? Options:
  A) light and combustible
  B) light and non-combustible
  C) heavy and combustible
  D) heavy and non-combustible
  Show Answer
  The correct answer is B .