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 1631:

  An element has an atomic number of 8 and a mass number of 16. How many neutrons does this element have?

  Options:
  A) 24
  B) 16
  C) 8
  D) 32
  Show Answer
  The correct answer is C .
• Question 1632:

  1s², 2s², 2p⁶, 3s², 3p⁶, 3d⁷, 4s²

  An element with the electronic configuration above is a

  Options:
  A) non-metal
  B) metal
  C) transition element
  D) group two element
  Show Answer
  The correct answer is C .
• Question 1633: The mass of an atom is determined by Options:
  A) its ionization potential
  B) its electrochemical potential
  C) the number of protons and electrons
  D) the number of neutrons and protons
  E) the number of neutrons and electrons
  Show Answer
  The correct answer is D .
• Question 1634: zn + 2HCl → ZnCl₂ + H₂The rate of the above reaction will be greatly increased if Options:
  A) the zinc is in the powered form
  B) a greater volume of the acid is used
  C) a smaller volume of the acid is used
  D) the reaction vessel is immersed in an ice-bath
  E) the zinc is in the form of pellets
  Show Answer
  The correct answer is A .
• Question 1635: Which of the following physical properties decreases down a group in the periodic table? Options:
  A) Atomic radius
  B) Ionic radius
  C) Electropositivity
  D) Electronegativity
  Show Answer
  The correct answer is B .
• Question 1636: Which of the following gases can be collected by the method of downward delivery? Options:
  A) Chlorine
  B) Oxygen
  C) Ammonia
  D) Hydrogen
  Show Answer
  The correct answer is A .
• Question 1637: The pollutant that contributes to the depletion of the ozone layer is Options:
  A) CFCs
  B) NO₂
  C) SO₂
  D) CO
  Show Answer
  The correct answer is A .
• Question 1638: Addition of aqueous ammonia to a solution of Zn⁺⁺ gives a white precipitate which dissolves in an excess of ammonia because? Options:
  A) zinc is amphoteric
  B) zinc hydroxide is readily soluble
  C) zinc forms a complex which is readily soluble in excess ammonia
  D) ammonia solution is a strong base
  Show Answer
  The correct answer is C .
• Question 1639: The removal of rust from iron by treatment with tetraoxosulphate (IV) acid is based on the? Options:
  A) hydrolysis of the iron
  B) reaction of acid with base
  C) oxidationof the rust
  D) dehydration of the iron
  Show Answer
  The correct answer is D .
• Question 1640: A hydrocarbon has an empirical formula CH and a vapour density of 39. Determine its molecular formula.[C = 12, H = 1] Options:
  A) C₂H₆
  B) C₃H₈
  C) C₃H₄
  D) C₆H₆
  Show Answer
  The correct answer is D .