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 71:

  CH_4(g) + CI_2(g) $\to$ CH₂CI_(s) + HCI_g

  The major factor that influences the rate of the reaction above is

  Options:
  A) Concentration
  B) Catalyst
  C) Temperature
  D) Light
  Show Answer
  The correct answer is D .
• Question 72:

  

  Consider the solubility curves of three salts X, Y and Z given in the diagram. If each solution of the salt contains 200 g, and is heated to 100°C, which solution or solutions will deposit 100 g of the solute when suddenly cooled to 0°C?

  Options:
  A) X only
  B) Y only
  C) Z only
  D) X and Z
  E) Y and Z
  Show Answer
  The correct answer is E .
• Question 73: Millikan's contributions to the development of atomic theory is the determination of Options:
  A) charge on electron
  B) positive rays
  C) charge to mass ratio
  D) cathode rays
  Show Answer
  The correct answer is A .
• Question 74:

  Sodium reacts vigorously with water to produce

  Options:
  A) Sodium chloride (NaCl) and oxygen gas (O2)
  B) Sodium nitrate (NaNO3) and water (H2O)
  C) Sodium hydroxide (NaOH) and hydrogen gas (H2)
  D) Sodium oxide (Na2O) and hydrogen gas (H2)
  Show Answer
  The correct answer is C .
• Question 75:

  An element Z contains 80% of ${}_8^{16}$Z and 20% of ${}_8^{18}$Z. Its relative atomic mass is

  Options:
  A) 16.2
  B) 17.6
  C) 16.0
  D) 16.4
  Show Answer
  The correct answer is D .
• Question 76:

  What is the symbol used to represent an alpha particle?

  Options:
  A) α
  B) γ
  C) δ
  D) β
  Show Answer
  The correct answer is A .
• Question 77: The compound that is used as an anaesthetic is Options:
  A) CCl₄
  B) CH Cl₃
  C) CH₂Cl₂
  D) CH₃Cl
  Show Answer
  The correct answer is B .
• Question 78:

  Chlorine, consisting of two isotopes of mass numbers 35 and 37, has an atomic mass of 35.5.
  The relative abundance of the isotope of mass number 37 is?

  Options:
  A) 20
  B) 25
  C) 50
  D) 75
  Show Answer
  The correct answer is B .
• Question 79:

  I. It has a varied composition from one place to another.

  II. It constituents can be separated by physical means.

  III. It contains unreactive noble gases

  Which of the above shows that air is a mixture?

  Options:
  A) I and II only
  B) II and III only
  C) I and III only
  D) I, II and III
  Show Answer
  The correct answer is A .
• Question 80:

  When anhydrous cobalt chloride paper is exposed to water, what color change is observed?

  Options:
  A) From pink to blue
  B) From white to blue
  C) From blue to white
  D) From blue to pink
  Show Answer
  The correct answer is D .