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 1: In the preparation of carbon monoxide by heating ethanedioic acid with concentrated sulphuric acid, the concentrated sulphuric acid act as? Options:
  A) an oxidizing agent
  B) a reducing agent
  C) a dehydrating agent
  D) a reaction medium
  E) a catalyst
  Show Answer
  The correct answer is C .
• Question 2:

  An example of a polysaccharide is?

  Options:
  A) Dextrose
  B) Mannose
  C) Glucose
  D) Starch
  Show Answer
  The correct answer is D .
• Question 3:

  A chemical reaction in which the hydration energy is greater than the lattice energy is referred to as

  Options:
  A) A reversible reaction
  B) A spontenous reaction
  C) An endothermic reaction
  D) An exothermic reaction
  Show Answer
  The correct answer is D .
• Question 4:

  The heat of formation of ethene, C${}_2$H${}_4$ is 50 kJmol${}^{-1}$, and that of ethane, C${}_2$H${}_6$ is -82kJmol${}^{-1}$. Calculate the heat evolved in the process:

  C${}_2$H${}_4$ + H${}_2$ $\to$ C${}_2$H${}_6$

  Options:
  A) -122kJ
  B) -132kJ
  C) -88kJ
  D) -60kJ
  Show Answer
  The correct answer is B .
• Question 5: Which of the following is NOT involved in the extraction of metals from their ores? Options:
  A) reduction with carbon
  B) reduction with other metals
  C) reduction by electrolysis
  D) oxidation with oxidizing agents
  Show Answer
  The correct answer is D .
• Question 6: In the reaction 1O^-₃ + 5l^- + 6H⁺ → 31₂ + 3H₂O, the oxidizing agent is? Options:
  A) H⁺
  B) l^-
  C) 1O^-
  D) l₂
  Show Answer
  The correct answer is C .
• Question 7: Which of the following statements is true? When the potassium atom forms its ion Options:
  A) it gains one electron and becomes neutral
  B) its atomic number decreases
  C) it achieves electronic configuration of orgon
  D) it loses one proton
  E) it loses one neutron
  Show Answer
  The correct answer is C .
• Question 8:

  0.16g of methane when burnt raises the temperature of 100g of water by 40°C. What is the of combustion of methane when if the heat capacity of water is 4.2 Jg^-1°C^-1?

  (CH₄ = 16)

  Options:
  A) 1,160 kJ mol^-1
  B) 1,180 kJ mol^-1
  C) 1,560 kJ mol^-1
  D) 1,600kJ mol^-1
  E) 1,680 kJ mol^-1
  Show Answer
  The correct answer is E .
• Question 9:

  In the laboratory preparation of oxygen, the gas cannot be collected by displacement of air because

  Options:
  A) the density of oxygen is greater than that of air
  B) the density of air is nearly the same as that of oxygen
  C) oxygen is a component of air
  D) air is an impure substance
  Show Answer
  The correct answer is A .
• Question 10: The fundamental difference between the three states of matter is the Options:
  A) shape of their particles
  B) number of particles in each state
  C) shape of the container they occupy
  D) degree of movement of their particles
  Show Answer
  The correct answer is D .