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 671:

  If the heat of combustion of hydrogen is -285.8kJ,

  What is the heat of formation of water?

  Options:
  A) +571.6 kJ
  B) -571.6 kJ
  C) -285.8 kJ
  D) +285.8 kJ
  Show Answer
  The correct answer is C .
• Question 672: During a titration experiment, 0.05 moles of carbon (lV) oxide is liberated. What is the volume of gas liberated? Options:
  A) 22.40 dm ³
  B) 11.20 dm ³
  C) 2.24 dm ³
  D) 1.12 dm ³
  Show Answer
  The correct answer is D .
• Question 673:

  A metallic oxide which reacts with both HCl and NaOH to give salt and water only can be classified as __________.

  Options:
  A) an acidic oxide
  B) a basic oxide
  C) a neutral oxide
  D) an amphoteric oxide
  Show Answer
  The correct answer is D .
• Question 674: The presence of nitrogen in air is to slow down Options:
  A) respiration and combustion
  B) combustion and corrosion
  C) corrosion and respiration
  D) respiration and transpiration
  Show Answer
  The correct answer is B .
• Question 675: How many unpaired electron(s) are there in the nitrogen sub-levels/ Options:
  A) 3
  B) 2
  C) 1
  D) none
  Show Answer
  The correct answer is A .
• Question 676: When a solution of ammonium trioxocarbonate (IV) is added to a solution of an unknown salt, a white precipitate which is soluble in dilute hydrochloric acid but insoluble in ethanoic acid is formed. This indicates the presence of Options:
  A) Ca²⁺
  B) Na⁺
  C) Zn²⁺
  D) K⁺
  Show Answer
  The correct answer is A .
• Question 677: The phenomenon whereby sodium trioxocarbonate (IV) decahydrate loses some of its water of crystallization on exposure to the atmosphere is known as? Options:
  A) deliquescene
  B) hygroscopy
  C) effervescence
  D) efflorescence
  Show Answer
  The correct answer is D .
• Question 678: The nucleus of the isotopes tritium contains Options:
  A) two neutrons with no protons
  B) one neutron and one proton
  C) two neutrons and one proton
  D) two neutrons, one proton and one electron
  Show Answer
  The correct answer is C .
• Question 679:

  The IUPAC name of the compound CF${}_3$CHBrCl is

  Options:
  A) 2-chloro-2-bromo-1,1,1-trifluoroethane
  B) 2-bromo-2-chloro-1,1,1-trifluoroethane
  C) 1-bromo-1-chloro-2,2,2-trifluoroethane
  D) 1,1,1-trifluoro-2-bromo-2-chloroethane
  Show Answer
  The correct answer is B .
• Question 680:

  What current in amperes will deposit 2.7g of aluminium in 2 hours?

  [Al = 27, F = 96 500 C mol^-1]

  Options:
  A) 32
  B) 8
  C) 4
  D) 16
  Show Answer
  The correct answer is C .