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 951:

  A compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. If the molar mass of the compound is 180. Find the molecular formula.

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

  Options:
  A) C${}_3$H${}_6$O${}_3$
  B) C${}_6$H${}_6$O${}_3$
  C) C${}_6$H${}_{12}$O${}_6$
  D) CH${}_2$O
  Show Answer
  The correct answer is C .
• Question 952: By means of filtration, one component can be obtained pure from an aqueous mixture of sodium chloride and Options:
  A) potassium nitrate
  B) sand
  C) lead nitrate
  D) sugar (glucose)
  E) starch
  Show Answer
  The correct answer is B .
• Question 953: The soft solder used for welding and plumbing is alloy of Options:
  A) lead and tin
  B) iron and tin
  C) lead and zinc
  D) iron and zinc
  Show Answer
  The correct answer is A .
• Question 954: The reaction between sulphur (IV) oxide and oxygen is represented by the equilibrium reaction 2SO_2(g) + O_2(g) ↔ 2SO_3(g), ∆H = -196 kJ. What factor would influence increased production of SO_3(g)? Options:
  A) Addition of a suitable catalyst
  B) Increase in the temperature of the reaction
  C) Decrease in the temperature of the reaction
  D) Decrease in the concentration of SO_2(g)
  Show Answer
  The correct answer is C .
• Question 955:

  

  Use the diagram to answer this question.

  The colour of the fountain water is

  Options:
  A) blue
  B) orange
  C) red
  D) yellow
  Show Answer
  The correct answer is C .
• Question 956: When marble is heated to about 1473 K, another white solid is obtained which reacts vigorously with water to give an alkaline solution. The solution contains? Options:
  A) NaOH
  B) KOH
  C) Mg(OH)₂
  D) Zn(OH)₂
  E) Ca(OH)₂
  Show Answer
  The correct answer is E .
• Question 957: Which one of these compounds will NOT give an oxygen gas on heating? Options:
  A) Manganese dioxide
  B) Hydrogen peroxide
  C) Zinc nitrate
  D) Sodium nitrate
  E) Ammonium nitrate
  Show Answer
  The correct answer is E .
• Question 958: If a gas occupies a container of volume 146 cm³ at 18°C and 0.97`atm, its volume 146cm³ at s.t.p is? Options:
  A) 133
  B) 146
  C) 266
  D) 292
  Show Answer
  The correct answer is A .
• Question 959:

  

  Use the above options to the question. The products formed on hydrolysis of

  Options:
  A) A
  B) B
  C) C
  D) D
  E) E
  Show Answer
  The correct answer is C .
• Question 960: In the extraction of aluminum from purified bauxite by electrolysis, cryolite is used because Options:
  A) it makes bauxite a better conductor of electricity
  B) it makes bauxite melt at a lower temperature
  C) it makes aluminium purer
  D) it prevents aluminium from getting oxidized
  E) it protects the carbon electrodes used in the process
  Show Answer
  The correct answer is B .