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 231: Methanoic acid mixes with water in all proportions and has about the same boiling point as water which of the following methods would you adopt to obtain pure water from a mixture of stand, water and methanoic acid? Options:
  A) fractional distillation
  B) filtration followed by distillation
  C) neutralization with sodium hydroxide followed by distillation
  D) esterification with ethanol followed by distillation
  E) neutralization with sodium hydroxide followed by filtration
  Show Answer
  The correct answer is B .
• Question 232: CaO_s + H₂O_(l) → Ca(OH)_2(s) ΔH -65 kj. The process represented by the above equation is known as? Options:
  A) dissolution
  B) slaking
  C) liming
  D) mortaring
  Show Answer
  The correct answer is B .
• Question 233:

  

  50 cm³ of sulphur (lV) oxide, 800 cm³ of carbon (IV) oxide will respectively saturate 1.0cm³ of water at 15^oC. Which of the following is suitable for demonstrating the fountain experiment?

  Options:
  A) Sulphur (IV) oxide and hydrogen chloride.
  B) Carbon (IV) oxide and ammonia
  C) Ammonia and hydrogen chloride
  D) Carbon (IV) oxide and Sulphur (IV) oxide
  Show Answer
  The correct answer is C .
• Question 234: Oxidation is the process of? Options:
  A) gain of electrons
  B) loss of electrons
  C) gain of hydrogen
  D) loss of oxygen
  E) addition of an electropositive element to a substance
  Show Answer
  The correct answer is B .
• Question 235: The arrangement of particles in crystal lattices can be studied using Options:
  A) X - rays
  B) γ - rays
  C) α - rays
  D) β - rays
  Show Answer
  The correct answer is A .
• Question 236:

  4g each of aluminium foil and aluminium powder were introduced respectively into flasks P and Q.

  Flask P was treated with warm bench sodium hydroxide and all the aluminium dissolved in one hour. Flask Q was treated with cold sodium hydroxide and all the aluminium dissolved in 10 minutes. What was responsible for Q reacting faster than P?

  Options:
  A) There were more aluminium atoms in Q than P
  B) The heat given off in retarded the reaction
  C) Q generated more pressure than P during the reaction
  D) P generated more pressure than Q
  E) Q has a greater surface area for the reaction than P
  Show Answer
  The correct answer is E .
• Question 237: The maximum number of electrons in the L shell of an atom is Options:
  A) 2
  B) 8
  C) 18
  D) 32
  Show Answer
  The correct answer is B .
• Question 238: Nitrogen obtained from the liquefaction of air has a higher density than that obtained from nitrogen containing compounds because the former contains Options:
  A) water vapour
  B) oxygen
  C) carbon (IV) oxide
  D) rare gases
  Show Answer
  The correct answer is D .
• Question 239: 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 240:

  Electrons enter into orbitals in order of increasing energy as exemplified by?

  Options:
  A) 1S${}^2$2S${}^2$2PX${}^2$2py${}^2$2pz${}^0$3s${}^0$
  B) 1S${}^2$2S${}^2$2PX${}^2$2py${}^1$2pz${}^1$3s${}^0$
  C) 1S${}^2$2S${}^2$2PX${}^1$2py${}^1$2pz${}^1$3s${}^1$
  D) 1S${}^2$2S${}^2$2PX${}^2$2py${}^2$2pz${}^0$3s${}^1$
  Show Answer
  The correct answer is B .