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 911: A rock sample was added to cold dilute HNO₃. The gas evolved was passed into a solution of acidified K₂Cr₂O₇ and the solution turned green. The sample contains Options:
  A) Cl^-
  B) NO₃^-
  C) SO₃^2-
  D) SO₄^2-
  Show Answer
  The correct answer is C .
• Question 912: If an equilibrium reaction has ΔH > 0, the reaction will proceed favourably in the forward direction at Options:
  A) High temperature
  B) Any temperature
  C) Low temperature
  D) Minimum temperature
  Show Answer
  The correct answer is A .
• Question 913: Ethene is prepared industrially by Options:
  A) Reforming
  B) Polymerization
  C) Distillation
  D) Cracking
  Show Answer
  The correct answer is D .
• Question 914: A hydrogen atom which has lost an electron contains Options:
  A) one proton only
  B) one neutron only
  C) one proton and one neutron
  D) one proton, one electronic and one neutron
  Show Answer
  The correct answer is A .
• Question 915: When iron is exposed to moist air, it gradually rusts. This is due to the formation of Options:
  A) hydrate iron (III) oxide
  B) anhydrous iron (III) oxide
  C) anhydrous iron (II) oxide
  D) hydrate iron (II) oxide
  Show Answer
  The correct answer is A .
• Question 916:

  A sample of hard water contains some calcium sulphate and calcium hydrogen carbonate. The total hardness may therefore be removed by

  Options:
  A) boiling the water
  B) adding excess calcium hydroxide
  C) adding a calculated amount of calcium hydroxide
  D) adding sodium carbonate
  Show Answer
  The correct answer is D .
• Question 917:

  What is the mass (in grams) of 500 mL of ethanol? (density of ethanol = 0.789 g/mL)

  Options:
  A) 394.5 mL
  B) 500 mL
  C) 394.5 g
  D) 500 g
  Show Answer
  The correct answer is C .
• Question 918:

  Which of the following statements is true regarding the melting and boiling points of pure substances?

  Options:
  A) The boiling point is always higher than the melting point
  B) The melting point is always higher than the boiling point
  C) The melting and boiling points are always the same for all substances
  D) The melting and boiling points can vary depending on the substance
  Show Answer
  The correct answer is D .
• Question 919:

  

  The IUPAC nomenclature for the compound above is

  Options:
  A) 4-methylpent-1-ene
  B) 3-methylpent-2-ene
  C) 2-methylpent-1ene
  D) 2-methylpent-4-ene
  Show Answer
  The correct answer is A .
• Question 920: The synthetic detergents are preferred to soap for laundry using hard water because? Options:
  A) detergents are water soluble while soap is not
  B) the calcium salts of detergents are water soluble
  C) the magnesium salt of soap is soluble in hard water
  D) soap does not have a hydrocarbon terminal chain
  Show Answer
  The correct answer is B .