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 421: If chlorine is bubbled into water and the resulting yellowish-green solution is exposed to bright sunlight for a while, the solution will decompose giving out Options:
  A) oxygen and leaving behind aqueous hydrochloric acid
  B) chlorine and oxygen
  C) oxygen, hydrogen and chlorine
  D) oxygen, thereby producing hypochlorous acid
  Show Answer
  The correct answer is A .
• Question 422: In the oil drop experiment, Millikan determined the? Options:
  A) charge to mass ratio of the electron
  B) mass of the electron
  C) charge of the electron
  D) mass of the proton
  Show Answer
  The correct answer is C .
• Question 423: the elements that belong to the third period of the periodic table are Options:
  A) Li, Be, Al and P
  B) Na, P, O and Cl
  C) B, C, N and O
  D) Nz, Mg, S and Ar
  Show Answer
  The correct answer is D .
• Question 424: Water for town supply is chlorinate to make it free from Options:
  A) bad colour
  B) bacteria
  C) temporary hardness
  D) permanent hardness
  Show Answer
  The correct answer is B .
• Question 425: The drying agent suitable for drying ammonia is Options:
  A) Calcium Chloride
  B) Calcium Oxide
  C) Phosphorus(V) Oxide
  D) Concentrated H₂SO₄
  Show Answer
  The correct answer is B .
• Question 426:

  The fourteen elements (atomic number 90-103) after actinium are called?

  Options:
  A) Actinoids
  B) Nucleotides
  C) Pre-actinum elements
  D) Atomic elements
  Show Answer
  The correct answer is A .
• Question 427:

  Which halogen is a gas at room temperature and is pale yellow in color?

  Options:
  A) Chlorine (Cl)
  B) Fluorine (F)
  C) Iodine (I)
  D) Bromine (Br)
  Show Answer
  The correct answer is B .
• Question 428: Which of the following combinations of conditions may increase the rate of a chemical reaction? Options:
  A) Decrease in temperature, increase in concentration of the reactants
  B) Increase in temperature, addition of a catalyst, decrease in the surface area of the reactants
  C) Increase in temperature, increase in concentration, addition of a catalyst and increase in the surface area of the reactants
  D) Decrease in temperature concentration and surface area of the reactants
  E) Additionof a catalyst and in the absence of light
  Show Answer
  The correct answer is C .
• Question 429: 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 430: A chemical reaction which the hydration energy is greater than the lattice energy is referred to as Options:
  A) a spontaneous reaction
  B) an endothermic reaction
  C) an exothermic reaction
  D) a reversible reaction
  Show Answer
  The correct answer is C .