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 571: The main impurity in iron ore during the extraction of iron is Options:
  A) Silicon (IV) oxide
  B) Carbon (IV) oxide
  C) Calcium trioxosilicate
  D) Sulphur (II) oxide
  Show Answer
  The correct answer is A .
• Question 572: Hydrogen is used in oxy-hydrogen flames for melting metals because it Options:
  A) evolves a lot of heat when burnt
  B) combines explosively with oxygen
  C) is a very light gas
  D) is a rocket fuel
  Show Answer
  The correct answer is A .
• Question 573: The chemical used for coagulation in water purification is Options:
  A) Aluminium tetraoxosulphate (VI)
  B) Copper tetraoxosulphate (VI)
  C) Sodium tetraoxosulphate (VI)
  D) Calcium tetraoxosulphate (VI)
  Show Answer
  The correct answer is A .
• Question 574: 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 575: In the redox reaction 2Fe²⁺ + CI₂ → 2Fe ^{3 +} + 2Cl Options:
  A) Cl₂ is reduced because it has lost electrons
  B) Cl₂ is reduced because its oxidation number has decreased
  C) Cl₂ is reduced because its molecule is change to two ions
  D) Fe²⁺ is reduced because it has lost electrons
  E) Fe²⁺ is reduced because it has gained electrons
  Show Answer
  The correct answer is B .
• Question 576: Which of the following compounds can be represented by the molecular formula C₂H₆O? Options:
  A) Propanel
  B) Ethanol
  C) Methanoic acid
  D) Glucose
  Show Answer
  The correct answer is B .
• Question 577: What is the volume of energy required to burn 45cm3 of mixture at S.T.P Options:
  A) 135.0cm³
  B) 150.0cm³
  C) 45.0cm³
  D) 90.0cm³
  Show Answer
  The correct answer is D .
• Question 578:

  

  The diagram above (Fig.3) shows the energy profile for the reaction A + B + = C + D From this diagram, it is clear that the reaction is

  Options:
  A) spontaneous
  B) isothermal
  C) adiabatic
  D) exothermic
  E) endothermic
  Show Answer
  The correct answer is D .
• Question 579: All these are electromagnetic waves except Options:
  A) White light
  B) Photon
  C) X-ray
  D) Infrared
  Show Answer
  The correct answer is B .
• Question 580:

  What is the empirical formula of a compound containing 40.00% carbon, 6.67% hydrogen, and 53.33% oxygen by mass?

  Options:
  A) C${}_4$H${}_8$O${}_4$
  B) CH${}_2$O
  C) C${}_2$H${}_4$O${}_2$
  D) C${}_3$H${}_6$O${}_3$
  Show Answer
  The correct answer is B .