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 1171:

  What is the chemical formula of rust, which is formed on the surface of iron in the presence of oxygen and moisture?

  Options:
  A) Fe${}_3$O${}_4$
  B) FeO
  C) Fe(OH)3
  D) Fe${}_2$O${}_3$
  Show Answer
  The correct answer is D .
• Question 1172: The allotropy of carbon used in the decolourization of sugar is Options:
  A) Graphite
  B) Soot
  C) Charcoal
  D) Lampblack
  Show Answer
  The correct answer is C .
• Question 1173: In the extraction of iron, which of the following reactions does NOT take place in the blast furnace? Options:
  A) CO₂ + C → 2CO
  B) 2Fe₂O₃ + 3C → 4Fe + 3CO₂
  C) Fe₂O₃ + 3C → 2Fe + 3CO₂
  D) CaCO₃ → CaO + CO₂
  E) CaO + SiO₂ → CaSiO₃
  Show Answer
  The correct answer is B .
• Question 1174: If d represents the density of a gas and K is a constant, the rate of gaseous diffusion r is related to d by the equation? Options:
  A) r = k/√d
  B) r = kd
  C) r =k/d
  D) r = k √d
  Show Answer
  The correct answer is A .
• Question 1175: The difference between colloides and and suspensions is brought out clearly by the fact that while colloids? Options:
  A) do not scatter light, suspensions do
  B) can be separated by filtration, suspension cannot be so separated
  C) can be separated by a membrane, suspensions cannot
  D) do not settle out on standing, suspensions do
  Show Answer
  The correct answer is D .
• Question 1176: When a current I was passed through an electrolyte solution for 40 minutes, a mass X g of a univalent metal was deposited at the cathode. What mass of the metal will be deposited when a current 2I is passed through the solution for 10 minutes? Options:
  A) X/4 g
  B) X/2 g
  C) 2X g
  D) 4X g
  Show Answer
  The correct answer is B .
• Question 1177: Which of the following is NOT an alkali? Options:
  A) NH₃
  B) Mg(OH)₂
  C) Ca(OH)₂
  D) NaOH
  Show Answer
  The correct answer is A .
• Question 1178: Ammonia gas is normally dried with? Options:
  A) concentrated sulphuric acid
  B) quicklime
  C) anhydrous calcium chloride
  D) magnesium sulphate
  Show Answer
  The correct answer is B .
• Question 1179:

  

  Which of the following compounds is a secondary alkanol?

  Options:
  A) A
  B) B
  C) C
  D) D
  Show Answer
  The correct answer is A .
• Question 1180: When dissolved in water, NaOH flakes show Options:
  A) An endothermic change
  B) An exothermic change
  C) A slow reaction
  D) A rapid reaction
  Show Answer
  The correct answer is B .