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 381:

  

  The diagram shown above represents the solubility curves of two salts, X and Y, in water, use this diagram to answer the question. If 80 g each of X and Y are taken up in 100 g of water at 353 K we shall have

  Options:
  A) only 10g of X undissolved
  B) only 16 g of Y undissolved
  C) 10 g of X and 16 g of Y undissolved
  D) all X and Y dissolved
  E) all X and Y undissolved
  Show Answer
  The correct answer is D .
• Question 382: Water can be obtained as the only product during Options:
  A) combustion of hydrocarbons
  B) neutralization of an acid by base
  C) combustion of hydrogen
  D) electrolysis of brine
  E) boiling water
  Show Answer
  The correct answer is C .
• Question 383:

  

  The figure above shows the electrolysis of molten sodium chloride. Z is the

  Options:
  A) anode where the Cl${}^{-}$ ions are oxidized
  B) cathode where the Cl${}^{-}$ ions are reduced
  C) anode where the Na${}^{+}$ ions are reduced
  D) cathode where the Na${}^{+}$ ions are oxidized
  Show Answer
  The correct answer is A .
• Question 384: The alkanol obtained from the production of soap is Options:
  A) ethanol
  B) glycerol
  C) methanol
  D) propanol
  E) glycol
  Show Answer
  The correct answer is B .
• Question 385: A solution containing chloride ions gives white precipitate with silver trioxonitrate(V) Solution. The precipitate will be insoluble in dilute? Options:
  A) HNO ₃ but soluble in ammonia solution
  B) HNO₃ and ammonia solution
  C) HCl but soluble in ammonia solution
  D) HCl and in ammonia solution
  Show Answer
  The correct answer is A .
• Question 386: What current in ampere will deposit 0.27g of aluminium in 2 hours? [Al = 27, F = 96500C]. Options:
  A) 3.2
  B) 8
  C) 0.4
  D) 16
  Show Answer
  The correct answer is C .
• Question 387:

  Consider the equation below:

  Cr${}_2$O${}_7^{2-}$ + 6Fe${}^{2+}$ + 14H${}^{+}$ $\to$ 2Cr${}^{3+}$ + 6Fe${}^{3+}$ + 7H${}_2$O.

  The oxidation number of chromium changes from

  Options:
  A) +5 to +3
  B) +6 to +3
  C) -2 to +3
  D) +7 to +3
  Show Answer
  The correct answer is B .
• Question 388:

  The following compounds are given with their corresponding boiling points.

  Compound Boiling Point

  i.................................14°C

  ii................................24°C

  iii................................0°C

  iv................................120°C

  V.................................-2°C

  From the above information, indicate which of the following is correct?

  Options:
  A) All the compounds are gaseous at 20 °C
  B) One of the compounds is gaseous at 20 °C
  C) Two of the compounds are gaseous at 20 °C
  D) Three of the compounds are gaseous at 20 °C
  E) None of the compounds is gaseous at 20 °C
  Show Answer
  The correct answer is D .
• Question 389: Dynamic equilibrium describes a situation where Options:
  A) a reaction gives back the reactant
  B) te concentration of the reactant and products is equal
  C) both forward and and reverse reactions proceed at the same rate
  D) reactants are converted to products
  Show Answer
  The correct answer is C .
• Question 390: The maximum number of electrons in the L shell of an atom is Options:
  A) 2
  B) 8
  C) 18
  D) 32
  Show Answer
  The correct answer is B .