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 161: A major process involved in the softening of hard water is the? Options:
  A) conversation of a soluble calcium salt to its trioxoncarbonate (lV)
  B) decomposition of calcium rioxocarbonate (lV)
  C) conversion of an insoluble calcium salts to its trioxocarbonate (lV)
  D) oxidation of calcium atoms to its ions
  Show Answer
  The correct answer is A .
• Question 162: How many cations will be produced from a solution of potassium aluminium tetraoxosulphate (VI)? Options:
  A) 3
  B) 4
  C) 1
  D) 2
  Show Answer
  The correct answer is D .
• Question 163:

  Which of the compounds is composed of Al, Si, O and H?

  Options:
  A) Epson salt
  B) Limestone
  C) Clay
  D) Urea
  Show Answer
  The correct answer is C .
• Question 164: The distance between the nuclei of chlorine atoms in a chlorine molecule is 0.194 mm. The atomic radius of chlorine atom is Options:
  A) 0.097 mm
  B) 0.194 mm
  C) 0.388 mm
  D) 2.388 mm
  Show Answer
  The correct answer is A .
• Question 165: The octane number of a fuel whose performance is the same as that of a mixture of 55 g of 2,2,4- trimethly pentane and 45 g of n-heptane is ? Options:
  A) 45
  B) 55
  C) 80
  D) 100
  Show Answer
  The correct answer is B .
• Question 166: The basic assumption in the kinetic theory of gases that the collisions of the gaseous molecules are perfectly elastic implies that the Options:
  A) forces of attraction and repulsion are in equilibrium
  B) gaseous molecules can occupy any available space
  C) gaseous molecules will continue their motion indefinitely
  D) gases can be compressed
  Show Answer
  The correct answer is C .
• Question 167: ¹⁴₇N + X → ¹⁷₈O + ¹₁ H. In the above reaction, X is a? Options:
  A) neutron
  B) helium atom
  C) litgium atom
  D) deuterium atom
  Show Answer
  The correct answer is B .
• Question 168: The colour changes observed when testing for reducing agents using acidified potassium heptaoxodichromate (IV) solution is Options:
  A) yellow to purple
  B) orange to green
  C) green to orange
  D) purple to yellow
  Show Answer
  The correct answer is B .
• Question 169:

  CH₃-CH-CH₃

  CH₂CI Is known as?

  Options:
  A) 1-chloro-2-methylbutane
  B) 1-chloro-2-methylpropane
  C) 2-chloromethylpropane
  D) 1-chloro-2, 2-dimethylethane
  Show Answer
  The correct answer is B .
• Question 170: What happens when the nitrates of potassium, calcium, zinc and copper are separately heated? Options:
  A) All the nitrate will decompose to their respective metals
  B) The nitrates of calcium and potassium will decomposes to their nitrites
  C) Only copper nitrate decomposes to the metal
  D) Only the nitrates of zinc and copper will decompose to their oxides
  E) The nitrates of calcium, zinc and copper decompose to their oxides
  Show Answer
  The correct answer is E .