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 11: The gas that gives brown colouration in brown ring test is Options:
  A) NO
  B) CO₂
  C) NO₂
  D) CO
  Show Answer
  The correct answer is A .
• Question 12: Which of the following, in clear solution, forms a white precipitate when carbon (IV) oxide is bubbled into it for a short time? Options:
  A) KOH
  B) NaOH
  C) Ca(OH)₂
  D) AI(OH)₃
  Show Answer
  The correct answer is C .
• Question 13:

  2H_2(g) + O_2(g) → 2H₂ O_(g)

  In the reaction above, what volume of hydrogen would be left over when 300 cm³ of oxygen and 1000 cm³ of hydrogen are exploded in a sealed tube?

  Options:
  A) 200 cm³
  B) 400 cm³
  C) 600 cm³
  D) 700 cm³
  Show Answer
  The correct answer is B .
• Question 14: What is the partial pressure of hydrogen gas collected over water at standard atmospheric pressure and 25^oC if the saturation vapour pressure of water at saturation vapour pressure of water is 23 mm Hg at that temperature? Options:
  A) 737 mm Hg
  B) 763 mm Hg
  C) 777 mm Hg
  D) 783 mm Hg
  Show Answer
  The correct answer is A .
• Question 15: Allotropes are elements having? Options:
  A) different physical but the same chemical properties
  B) different chemical but the same physical properties
  C) the same chemical and physical properties
  D) different atomic structure
  E) the same position in the periodic table
  Show Answer
  The correct answer is A .
• Question 16: The ability of ionic solids is generally due to the? Options:
  A) negative electron affinity of most atoms
  B) crystal lattice forces
  C) electron pair sharing
  D) positive ionization potentials
  Show Answer
  The correct answer is B .
• Question 17:

  In the upper atmosphere, the ultra-violet light breaks off a free chlorine atom from chlorofluorocarbon molecule. The effect of this is that the free chlorine atom will

  Options:
  A) be very reactive and will attack ozone
  B) be non-reactive and will not attack ozone
  C) not change the level of ozone in the atmosphere
  D) increase the level of ozone in the atmosphere
  Show Answer
  The correct answer is A .
• Question 18: Which of the following alkanes has the highest boiling point? Options:
  A) Pentane
  B) Ethane
  C) Propane
  D) Methane
  Show Answer
  The correct answer is A .
• Question 19: Indicate which of the following statements is not true as we move from left to right along the periodic Table: Options:
  A) atomic number of elements increases
  B) atomic mass of elements increases
  C) electropositive character of elements increases
  D) electronegative character of elements increases
  E) number of electrons in the outermost orbits of element increases
  Show Answer
  The correct answer is C .
• Question 20: Alkaline hydrolysis of naturally occurring fats and oils yields Options:
  A) fats and acids
  B) soaps and glycerol
  C) margarine and butter
  D) esters
  E) detergents
  Show Answer
  The correct answer is B .