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 1121: The dissolution of common salt in water is a physical change because Options:
  A) the salt can be obtained by crystallization
  B) the salt can be recovered by the evaporation of water
  C) heat is not generated during mixing
  D) the solution will not boil at 100^oC
  Show Answer
  The correct answer is C .
• Question 1122: The mathematical expression of PH is Options:
  A) log ₁₀[OH^-]
  B) log ₁₀1/[H ₃ O⁺]
  C) log ₁₀[H ₃ O⁺]
  D) log ₁₀1/[OH ^-]
  Show Answer
  The correct answer is B .
• Question 1123: A mixture of starch solution and potassium iodide was placed in a test tube. On adding dilute tetraoxosulphate (lV) acid and then K₂Cr₂O₇ solutions, a blue-black colour was produced. In this reaction, the? Options:
  A) iodide is oxidized
  B) tetraoxosulphate (Vl) acid acts as an oxidizing agent
  C) starch has been oxidized
  D) K₂Cr₂O₇ is oxidized
  Show Answer
  The correct answer is C .
• Question 1124: Sodium metal is always kept under oil because it Options:
  A) Readily reacts with water
  B) Is reduced by atmospheric nitrogen
  C) Reacts vigorously on exposure to air
  D) Reacts with oxygen and carbon (IV) oxide
  Show Answer
  The correct answer is C .
• Question 1125:

  Which of the following types of alkanols undergo oxidation to produce alkanoic acids.I. Primary alkanols

  II. Secondary alkanols

  III. Tertiary alkanols

  Options:
  A) I, II and III
  B) I and II only
  C) III only
  D) I only
  Show Answer
  The correct answer is D .
• Question 1126: How many moles of oxygen molecules would be produced from the decomposition of 2.50 moles of potassium trioxochlorate (V)? Options:
  A) 2.50
  B) 3.50
  C) 3.75
  D) 7.50
  Show Answer
  The correct answer is C .
• Question 1127:

  A radioactive nucleus has a half-life of 20 years, starting with 100,000 particles, how many particles will be left exactly at the end of 40 years

  Options:
  A) 75,000 particles
  B) 35,000 particles
  C) 25,000 particles
  D) 50,000 particles
  Show Answer
  The correct answer is C .
• Question 1128: How many isomeric forms are there for the molecular formula C₃H₆Br₂? Options:
  A) 1
  B) 2
  C) 3
  D) 4
  E) 5
  Show Answer
  The correct answer is D .
• Question 1129: An emulsion may be produced by shaking a detergent solution with Options:
  A) palm wine
  B) ethanoic acid
  C) palm oil
  D) water
  Show Answer
  The correct answer is C .
• Question 1130: Which of these pairs are synthetic and natural macromolecules respectively? Options:
  A) Haemoglobin and nylon, creatine and polyethylene
  B) Nylon and polyethlene, creatine and Haemoglobin
  C) Nylon and creatine, polyethylene and haemoglobin
  D) Polyethylene and creatine, nylon and haemoglobin
  Show Answer
  The correct answer is C .