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 891: In the electrolytic extraction of aluminum, the function of the molten cryolite is to Options:
  A) precipitate aluminium hdroxide
  B) lower the melting point of aluminium oxide
  C) act as a raw materials
  D) act as a solvent
  Show Answer
  The correct answer is B .
• Question 892: The intermediate product formed when ethanol is progressively oxidized to ethanoic acid with potassium heptaoxodichromate (IV) is Options:
  A) butanal
  B) ethanal
  C) methanal
  D) propanal
  Show Answer
  The correct answer is B .
• Question 893: In the electrolysis of a concentrated solution of sodium chloride using electrodes, which of the following ions are discharged at the cathode and anode respectively? Options:
  A) Na⁺ and Cl^-
  B) Na⁺ and OH^-
  C) H⁺ and OH^-
  D) H⁺ and Cl^-
  Show Answer
  The correct answer is D .
• Question 894:

  200cm${}^3$ of 0.50mol/dm${}^3$ solution of calcium hydrogen trioxocarbonate (IV) is heated. The maximum weight of solid precipitated is

  Options:
  A) 10g
  B) 25g
  C) 20g
  D) 15g
  Show Answer
  The correct answer is A .
• Question 895:

  What volume of (dm${}^3$) of water will be added to 10dm${}^3$ of 2.0 mol/dm${}^3$ HCL acid solution to give a final solution of 0.5 mol/dm${}^3$?

  Options:
  A) 30
  B) 40
  C) 20
  D) 50
  Show Answer
  The correct answer is B .
• Question 896: Clothes should be properly rinsed with water after bleaching because Options:
  A) the bleach decolourizes the clothes
  B) chlorine reacts with fabrics during bleaching
  C) the clothes are sterilized during bleaching
  D) hydrogen chloride solution is produced during bleaching
  Show Answer
  The correct answer is D .
• Question 897: Coal fire should not be used in poorly ventilated rooms because ? Options:
  A) of the accumulation of CO₂ which causes dep sleep
  B) it is usually too hot
  C) of the acumulation of CO which causes suffocation
  D) it removes most most of the gases in the rooms
  Show Answer
  The correct answer is C .
• Question 898: An example of a polysaccharides is? Options:
  A) —dextrose
  B) mannose
  C) glucose
  D) starch
  Show Answer
  The correct answer is D .
• Question 899:

  A certain hydrocarbon on complete combustion at s.t.p produced 89.6dm${}^3$ of CO${}_2$ and 54g of water. The hydrocarbon should be

  Options:
  A) C${}_6$H${}_6$
  B) C${}_4$H${}_{10}$
  C) C${}_5$H${}_{10}$
  D) C${}_4$H${}_6$
  Show Answer
  The correct answer is D .
• Question 900:

  Suitable reagents for the laboratory preparation nitrogen are

  Options:
  A) sodium dioxonitrate(III) and ammonium chloride
  B) sodium trioxonitrate(V) and ammonium chloride
  C) sodium chloride and ammonium trioxonitrate(V)
  D) sodium chloride and ammonium di-ozonitrate(III)
  Show Answer
  The correct answer is A .