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 651: Which of the following gives a precipitation when treated with NaOH Solution? Options:
  A) AlCl₃
  B) NH₄Cl
  C) Na₂CO₃
  D) CH₃COONa
  Show Answer
  The correct answer is A .
• Question 652: An electron can be added to a halogen atom to form a halide ion with Options:
  A) 2 valence electrons
  B) 3 valence electrons
  C) 7 valence electrons
  D) 8 valence electrons
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  The correct answer is D .
• Question 653: A gas that will turn orange potassium heptaoxodichromate (lV) solution to clear green is? Options:
  A) sulphur (ii) oxide
  B) hydrogen sulphide
  C) sulphide (lV) oxide
  D) hydrogen chloride
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  The correct answer is A .
• Question 654: Unsaturated organic compounds are identified by decolourization of Options:
  A) silver bromine and potassium tetraoxomanganate (VII) solutions
  B) bromine water and acidified potassium tetraoxomanganate (VII) solution
  C) silver bromide solution and bromine water
  D) bromine water and alkaline potassium tetraoxomanganate (VII) solution
  Show Answer
  The correct answer is B .
• Question 655:

  The process or act of extracting a metal from its ore and refining it is called?

  Options:
  A) Extraction
  B) Metal mining
  C) Mettallurgy
  D) Prospecting
  Show Answer
  The correct answer is C .
• Question 656: Two gas cylinders contain ethylene (ethene) and acetylene respectively. One test which can be used to distinguish between them is by Options:
  A) passing each gas through bromine water
  B) passing each gas through dilute potassium permanganate solution
  C) passing each gas through silver nitrate solution
  D) treating each gas catalytically with excess hydrogen gas
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  The correct answer is C .
• Question 657:

  If the volume of a given mass of a gas at 0ºc is29.5cm${}^3$. What will be the volume of the gas at 15ºc, given that the pressure remains constant.

  Options:
  A) 31.6
  B) 62.2
  C) 32.7
  D) 31.1
  Show Answer
  The correct answer is D .
• Question 658:

  Consider the reaction

  A${}_{(s)}$ + 2B${}_{(g)}$ → 2C${}_{(aq)}$ + D${}_{(g)}$

  What will be the effect of a decrease in pressure on the reaction?

  Options:
  A) the equilibrium will shift
  B) rate of forward reaction will increase
  C) rate of backward reaction will increase
  D) rates of forward and backward reaction are not affected
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  The correct answer is B .
• Question 659: Which of the following gases may not be dried with concentrated sulphuric acid? Options:
  A) HCl
  B) N₂
  C) Cl₂
  D) SO₂
  E) NH₃
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  The correct answer is E .
• Question 660: When pollen grains are suspended in water and viewed through a microscope, they appear to be in a state of constant but erratic motion. This is due to? Options:
  A) convection currents
  B) small changes
  C) small changes in temperature
  D) a chemical reaction between the pollen grain and water
  E) the bombardment of the pollen grains by molecules of water
  Show Answer
  The correct answer is E .