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 781: 28.8 cm³ of nitrogen at 15°C is cooled to O°C at constant pressure, the new volume of nitrogen is? Options:
  A) 17.4 cm³
  B) 14.7 cm³
  C) 27.3 cm³
  D) 31.7 cm³
  Show Answer
  The correct answer is C .
• Question 782:

  Identify the reducing agent in the following reaction:
  Zn + CuSO${}_4$ ZnSO${}_4$ + Cu

  Options:
  A) Cu
  B) Zn
  C) ZnSO${}_4$
  D) CuSO${}_4$
  Show Answer
  The correct answer is B .
• Question 783: An endothermic reaction is one during which heat is.....and can be represented by the symbol.... which of the following combinations can be used accurately to complete the above definition? Options:
  A) liberated, -$\mathrm{\Delta }$H
  B) liberated, +$\mathrm{\Delta }$H
  C) absorbed, -$\mathrm{\Delta }$H
  D) absorbed, +$\mathrm{\Delta }$H
  E) absorbed, +$\mathrm{\Delta }$G
  Show Answer
  The correct answer is D .
• Question 784: Which of these require crystallization most? Options:
  A) Drug making
  B) Cement making
  C) Paint making
  D) Perfume making
  Show Answer
  The correct answer is A .
• Question 785:

  To what temperature must a gas at 273k be heated in order to double both its volume and pressure?

  Options:
  A) 298K
  B) 546K
  C) 819K
  D) 1092K
  Show Answer
  The correct answer is D .
• Question 786: The carbon atoms on ethane are Options:
  A) sp² hybridized
  B) sp³ hybridized
  C) sp⁴ hybridized
  D) sp hybridized
  Show Answer
  The correct answer is B .
• Question 787: The combustion of ethene, C ₂H ₄, is given by the equation C ₂H ₄ + 30 ₂ → 2CO₂ + 2H₂ O; ∆H = - 1428 KJ. If the molar heats of formation of water and carbon (IV) oxide are - 286 kJ and - 396 kJ respectively, calculate the molar heat of formation of ethene in KJ Options:
  A) - 2792
  B) + 2792
  C) - 64
  D) + 64
  Show Answer
  The correct answer is D .
• Question 788:

  The Sulphide which is insoluble in dilute hydrochloric acid is

  Options:
  A) FeS
  B) CuS
  C) ZnS
  D) Na2S
  Show Answer
  The correct answer is B .
• Question 789: In the reaction 1O^-₃ + 5l^- + 6H⁺ → 31₂ + 3H₂O, the oxidizing agent is? Options:
  A) H⁺
  B) l^-
  C) 1O^-
  D) l₂
  Show Answer
  The correct answer is C .
• Question 790:

  In the reaction:

  M + N → P

  ΔH = +Q kJWhich of the following would increase the concentration of the product?

  Options:
  A) Adding a suitable catalyst
  B) Increasing the concentration of P
  C) Increasing the temperature
  D) Decreasing the temperature
  Show Answer
  The correct answer is C .