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 1901: Which of the following equations show that a reaction is in equilibrium?
  Options:
  A) ΔG < O
  B) ΔG = ΔH – TΔS
  C) ΔG > O
  D) ΔG = O
  Show Answer
  The correct answer is D .
• Question 1902: If glucose is heated with concentration tetraoxosulphate (VI) acid, it will be dehydrated to Options:
  A) carbon
  B) carbon (IV) oxide
  C) ethene
  D) ethanol
  Show Answer
  The correct answer is A .
• Question 1903:

  A gas occupies a volume of 1.5 liters at a pressure of 2 atmospheres. If the pressure is increased to 4 atmospheres while the temperature remains constant, what will be the new volume of the gas?

  Options:
  A) 6 liters
  B) 1.5 liters
  C) 0.75 liters
  D) 3 liters
  Show Answer
  The correct answer is C .
• Question 1904: Oxyacetylene flame is used for iron-welding because it Options:
  A) Makes the iron metals solidify very quickly
  B) Combines with oxygen to give a pop sound
  C) Evolves a lot of heat when burnt
  D) Dissociates to produce carbon (IV) oxide and oxygen
  Show Answer
  The correct answer is C .
• Question 1905:

  Zn _(s) + CuSO ₄(aq) → ZnSO ₄(aq) + Cu _(s)

  In the reaction above, the oxidation number of the reducing agent changes from

  Options:
  A) 0 to + 4
  B) 0 to + 2
  C) + 1 to + 2
  D) + 1 to + 3
  Show Answer
  The correct answer is B .
• Question 1906:

  Which of the following statements about catalyst is false?

  Options:
  A) biological catalysts are called enzymes
  B) catalyst do not appear in the balanced equation
  C) catalyst reduce the activation energy for a reaction
  D) catalysts do not alter the mechanism of the reaction and never appear in the rate low
  Show Answer
  The correct answer is D .
• Question 1907: When carbondioxide is bubbled into limewater a white precipitate is formed. If the passage of the gas is continued, the precipitate disappears. The reason for this is Options:
  A) calcium carbonate is formed which on reaction dissolves
  B) calcium hydrogen carbonate is precipitated and then dissolves
  C) calcium carbonate is formed which on reaction with further carbondioxide forms solube calcium hydrogen carbonate
  D) concentration of the solution has occurred with the deposition of calcium hydroxide
  E) the solution has become saturated and solid carbondioxide has been deposited
  Show Answer
  The correct answer is C .
• Question 1908: Which of the following compounds will undergo polymerization reaction? Options:
  A) C₂H₄
  B) C₂H₅COOH
  C) C₂H₆
  D) C₂H₅OH
  Show Answer
  The correct answer is A .
• Question 1909:

  .....................P....Q.....R......S

  Proton..............13....16....17.....19

  Electron............13....16....17.....19

  Neutron.............14....16....35.....20Which of the four atoms P,q,R and in S in the above data can be described by the following properties relative atomic mass is greater than 30 but less than 40; it has an odd atomic number and forms a unipositive ion in solution?

  Options:
  A) P
  B) Q
  C) R
  D) S
  Show Answer
  The correct answer is D .
• Question 1910: A solid begins to melt when? Options:
  A) constituent particles acquires a greater kinetic energy
  B) energy of vibration of particles of the solid is less than the intermolecular forces
  C) constituent particles acquires energy above the average kinetic energy
  D) energy of vibration of particles of the solid equals the intermolecular forces
  Show Answer
  The correct answer is A .