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: According to charles' law, the volume of a gas becomes zero at Options:
  A) 0 ^oC
  B) -100 ^oC
  C) -273 ^oC
  D) -373 ^oC
  Show Answer
  The correct answer is C .
• Question 572: Which of the following statements is incorrect? Options:
  A) Calcium reacts with water to form calcium
  B) Magnesium reacts very slowly with water but faster with warm water
  C) Iron will not react with water in the absence of air
  D) Sodium reacts with water
  E) Copper reacts with steam
  Show Answer
  The correct answer is E .
• Question 573:

  

  The following graph demonstrates the rate of reaction between calcium carbonate (marble)and dilute hydrochloric acid. The graph shows that the rate of reaction is initially greatest when

  Options:
  A) the initial slope of the curve is steepest and this occur when small pieces of marble are used and is due to a small surface area of reactant
  B) the occur when large pieces of marble are used and is due to a small surface area of reactant
  C) the initial slope of the curve is steepest and this occurs when small pieces of marble are used and is due to a large surface area of reactant
  D) the initial slope of the curve is steepest and this occur when large surface area of reactant
  E) the initial slope of the curve is least steep and this occur when small pieces of marble are used and is due to the increased surface area of the reactant
  Show Answer
  The correct answer is C .
• Question 574: When chlorine Is passed into water and the resulting solution exposed to sunlight, the product formed are Options:
  A) Chlorine gas and hydrogen
  B) Oxygen and oxochlorate (I) acid
  C) Chlorine gas and oxochlorate (I) acid
  D) Hydrochloric acid and oxygen
  Show Answer
  The correct answer is D .
• Question 575: The coloured nature of transition metal ions are associated with their partially filled Options:
  A) f- orbital
  B) s- orbital
  C) p-orbital
  D) d-orbital
  Show Answer
  The correct answer is D .
• Question 576: 0.07g of a hydride of carbon occupies 56.0cm³ at S.T.P. when vaporized and contains 14.29% by mass of hydrocarbon is(C = 12, H = 1) Options:
  A) CH₄
  B) C₂H₂
  C) C₂H₄
  D) C₂H₆
  E) C₃H₈
  Show Answer
  The correct answer is C .
• Question 577:

  Consider the following exothermic reaction

  2SO_2(g) + O_2(g) ↔ 2SO_3(g)

  If the temperature of the reaction is reduced from 800°C to 500°C, an no other change takes place, then

  Options:
  A) the reaction rate increases
  B) concentration of SO₃ decreases
  C) concentration of SO₃ increases
  D) SO₂ gas becomes unreactive
  E) O₃ gas becomes unreactive
  Show Answer
  The correct answer is C .
• Question 578: The temperature of a body decreases when drops of liquid placed on it evaporate because? Options:
  A) the atmospheric vapour pressure has a cooling effect on the body
  B) a temperature gradient exists between the drops of liquid and the body causing the latter to vaporate
  C) the heat of vapourization is drawn from the body causing it to cool
  D) the random motion of the liquid molecules causes a cooling effect on the body
  Show Answer
  The correct answer is C .
• Question 579: If concentrated sulphric acid is added to sugar and warmed gently, the sugar changes from white to brown and finally to a black mas of carbon. In this reaction, concentrated sulphuric acid is acting as ? Options:
  A) a drying agent
  B) an oxidizing agent
  C) a dehydrated agent
  D) a reducing agent
  E) a hydrolysing agent
  Show Answer
  The correct answer is C .
• Question 580: Which of the following compounds will form a solution if exposed to air? Options:
  A) Na₂CO₃.10H₂O
  B) NaNO₃
  C) CuSO₄
  D) CaCl₂
  E) Na₂SO₄.10H₂O
  Show Answer
  The correct answer is D .