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 131:

  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 132:

  

  Z in diagram above represents

  Options:
  A) heat of reaction
  B) activation energy
  C) free energy
  D) entropy of reaction
  Show Answer
  The correct answer is A .
• Question 133:

  In which of the following will hydrogen form ionic compound?

  Options:
  A) HCL
  B) NaH
  C) NH${}_3$
  D) CH${}_4$
  Show Answer
  The correct answer is B .
• Question 134: Flow of current in electrolytes is due to the movement of Options:
  A) electrons
  B) Holes and electron
  C) Ions
  D) Charges
  Show Answer
  The correct answer is C .
• Question 135: Commercial bleaching can be carried out using Options:
  A) sulphur (IV) oxide and ammonia
  B) hydrogen sulphide and chlorine
  C) chlorine and sulphur (IV) oxide
  D) ammonia and chlorine
  Show Answer
  The correct answer is C .
• Question 136:

  The lanthanides and actinides are located in which block of the periodic table?

  Options:
  A) P-block
  B) S-block
  C) F-block
  D) D-block
  Show Answer
  The correct answer is C .
• Question 137:

  To obtain pure carbon(ii)oxide from its mixture with carbon(iv)oxide, the mixture should be?

  Options:
  A) Passed over heated copper(ii)oxide
  B) Bubbled through water
  C) Bubbled through conc H${}_2$SO${}_4$
  D) Bubbled through conc NAOH
  Show Answer
  The correct answer is D .
• Question 138: The processes which return carbon (IV) oxide to the atmosphere include Options:
  A) respiration, decay and combustion
  B) photosynthesis, respiration and transpiration
  C) ozone depletion, combustion and decay
  D) photosynthesis, decay and respiration
  Show Answer
  The correct answer is A .
• Question 139:

  

  The arrangement above can be used for the collection of

  Options:
  A) sulphur (IV) oxide
  B) ammonia
  C) hydrogen chloride
  D) nitrogen
  Show Answer
  The correct answer is C .
• Question 140:

  The solubility in mol dm^-3 of 20g of CuSO₄ dissolved in 100g of water at 180^o is

  [Cu = 64, S = 32, O =16]

  Options:
  A) 0.13
  B) 0.25
  C) 1.25
  D) 2.00
  Show Answer
  The correct answer is C .