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 11: The molecular formula of a common organic laboratory anaesthetic is Options:
  A) CHCl₃
  B) CHI₃
  C) CCl₄
  D) CHF₃
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  The correct answer is A .
• Question 12: CH₃COOC₂H₅(1) + H₂O₍₁₎ ⇌ CH ₃COOH _(aq) + C ₂H ₅OH _(aq)The purpose of H⁺ in the reaction above is to Options:
  A) increase the yield of products
  B) maintain the solution at a constant PH
  C) increase the rate of the hydrolysis
  D) decrease the rate of the reverse reaction
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  The correct answer is A .
• Question 13: Group 1 A metals are not found free in nature because they? Options:
  A) are of low melting and boiling points
  B) have weak metallic bonding
  C) conduct electricity and heat
  D) are very reactive
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  The correct answer is D .
• Question 14: 12 g of solid protassium chlorate (KCIO) were added to 40 g of water and heated to dissolve all the solid. As the solution cools, crystals of potassium chlorate at 66 ^oC. The solubility of potassium chlorate at 66 ^oC is therefore Options:
  A) 66
  B) 33
  C) 10
  D) 20
  E) 30
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  The correct answer is E .
• Question 15: A mixture of common salt, ammonium chloride and barium sulphate can best be separated by Options:
  A) addition of water followed by filtration then sublimation
  B) addition of water followed by sublimation then filtration
  C) sublimation followed by addition of water then filtration
  D) fractional distillation
  E) fractional crystallization
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  The correct answer is C .
• Question 16: In the chemical reaction A + B $\to$ C + D, more of D is formed? Options:
  A) if the concentrated of A is reduced
  B) if the concentrated of B is reduced
  C) if the concentrated of C is reduced
  D) if the concentration of C is increased
  E) if D is continuously removed from the reaction mixture
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  The correct answer is E .
• Question 17:

  Which of the following compounds is an example of an electrovalent bond?

  Options:
  A) NaCl (sodium chloride)
  B) CO2 (carbon dioxide)
  C) H2O (water)
  D) CH4 (methane)
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  The correct answer is A .
• Question 18: A polymerization reaction is one in which? Options:
  A) small molecules form giant molecules
  B) atoms form molecules
  C) giant molecules form small molecules
  D) molecules form volatile compounds
  E) a molecule rearranges itself
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  The correct answer is A .
• Question 19:

  

  The functional group represented in the compound above is

  Options:
  A) alkanol
  B) alanal
  C) alkanone
  D) alanoate
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  The correct answer is C .
• Question 20: A given mass of gas occupies 2 dm³ at 300k. At what temperature will its volume be doubled keeping the pressure constant? Options:
  A) 400k
  B) 480k
  C) 550k
  D) 600k
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  The correct answer is D .