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 841: The colour imparted to a flame by calcuium ion is Options:
  A) green
  B) blue
  C) brick-red
  D) yellow
  E) lilac
  Show Answer
  The correct answer is C .
• Question 842:

  Potassium trioxochlorate (V)has a solubility of 1.5 mol dm ^-3 at 45 ^oC.On cooling this solution to a temperature of 20 ^oC, the solubility was found to be 0.5 mol dm ^-3. What mass of KCIO ₃ was crystalized out?

  [K = 39, Cl = 35.5 O =16].

  Options:
  A) 1.00g
  B) 10.00g
  C) 12.25g
  D) 122.50g
  Show Answer
  The correct answer is D .
• Question 843:

  Chlorine gas is commonly used in the production of which of the following industrial compounds?

  Options:
  A) Chlorofluorocarbons (CFCs)
  B) Methane
  C) Ammonia
  D) Ethanol
  Show Answer
  The correct answer is A .
• Question 844: Which of the following compounds is used as a gaseous fuel? Options:
  A) CH₃ -CH₂ -CHO₂ -COOH
  B) CH₃ -C = CH
  C) CH₃ -CH₂ -CH₂ -CH₃
  D) CH₂ -CH₂ -CH₃
  Show Answer
  The correct answer is C .
• Question 845:

  

  The diagram shown above represents the solubility curves of two salts, X and Y, in water, use this diagram to answer the question. If the molar mass of X is 36 g, the number of moles of X dissolved at 343 K is

  Options:
  A) 0.2 moles
  B) 0.7 moles
  C) 1.5 moles
  D) 2.0 moles
  E) 3.0 moles
  Show Answer
  The correct answer is B .
• Question 846:

  Which of the following metals is the most essential in the regulation of blood volume, blood pressure and osmotic equilibrium?

  Options:
  A) Zinc
  B) Manganese
  C) Sodium
  D) Iron
  Show Answer
  The correct answer is C .
• Question 847:

  

  In the shown experiment (Fig. 1) the litmus paper will initially

  Options:
  A) be bleached
  B) turn green
  C) turn red
  D) turn blue
  Show Answer
  The correct answer is D .
• Question 848:

  An organic compound has an empirical formula CH₂O and vapour density of 45.

  What is the molecular formula?

  [C = 12, H = 1, O = 16]

  Options:
  A) C₃H₇OH
  B) C₂H₅OH
  C) C₃H₆O₃
  D) C₂H₄O₂
  Show Answer
  The correct answer is C .
• Question 849:

  The pollutant usually presents in a city which generates its electricity from coal?

  Options:
  A) fog
  B) carbon(ii)oxide
  C) smog
  D) sulphur(iv)oxide
  Show Answer
  The correct answer is D .
• Question 850: The salt that will form a precipitate soluble in excess ammonia solution is Options:
  A) Ca(NO₃)₂
  B) Cu(NO₃₎₂
  C) Mg(NO₃₎₂
  D) Al(NO₃₎₃
  Show Answer
  The correct answer is B .