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 931:

  When air which contains the gases Oxygen, nitrogen, carbondioxide, water vapour and the rare gases, is passed through alkaline pyrogallol and then over quicklime, the only gases left are;

  Options:
  A) nitrogen and carbondioxide
  B) the rare gases
  C) nitrogen and oxygen
  D) nitrogen and the rare gases
  Show Answer
  The correct answer is D .
• Question 932: When at equilibrium, which of the reactions below will shift to the right if the pressure is increased and the temperature is kept constant? Options:
  A) 2SO_3(g) ↔ 2SO_2(g) + O_2(g)
  B) 2CO_2(g) ↔ 2CO_(g) + O_2(g)
  C) 2H_2(g) + O_2(g) ↔ 2H₂O_(g)
  D) 2NO_(g) ↔ N_2(g) + O_2(g)
  Show Answer
  The correct answer is C .
• Question 933:

  Sodium reacts vigorously with water to produce

  Options:
  A) Sodium chloride (NaCl) and oxygen gas (O2)
  B) Sodium nitrate (NaNO3) and water (H2O)
  C) Sodium hydroxide (NaOH) and hydrogen gas (H2)
  D) Sodium oxide (Na2O) and hydrogen gas (H2)
  Show Answer
  The correct answer is C .
• Question 934:

  An element Z contains 80% of ${}_8^{16}$Z and 20% of ${}_8^{18}$Z. Its relative atomic mass is

  Options:
  A) 16.2
  B) 17.6
  C) 16.0
  D) 16.4
  Show Answer
  The correct answer is D .
• Question 935: The gas that is most useful in protecting humans against solar radiation is Options:
  A) chlorine
  B) ozone
  C) carbon (IV) oxide
  D) hydrogen sulphide
  Show Answer
  The correct answer is B .
• Question 936:

  

  The diagram represents

  Options:
  A) A spontaneous reaction
  B) An exothermic reaction
  C) A non-spontaneous
  D) An endothermic reaction
  Show Answer
  The correct answer is C .
• Question 937: Mortar is NOT used for under-water construction because Options:
  A) it hardens by lose of water
  B) its hardening doe not depend upon evaporation
  C) it requires concrete to harden
  D) it will be washed away by the flow of water
  Show Answer
  The correct answer is A .
• Question 938: Water is said to be temporarily hard when it contains Options:
  A) Ca (HCO₃)₂ and Mg (HCO₃)₂ salts
  B) Ca (HCO₃)₂ and CaCO₃ SALTS
  C) Mg(HCO₃)₂ and CaSO₄ salts
  D) CaSO₄ and Ca(HCO₃)₂ salts
  Show Answer
  The correct answer is A .
• Question 939:

  Which of the following could not be alkane?

  Options:
  A) C${}_4$H${}_{10}$
  B) C${}_5$H${}_{12}$
  C) C${}_7$H${}_{14}$
  D) C${}_8$H${}_{18}$
  Show Answer
  The correct answer is C .
• Question 940: The gas that is the most dangerous pollutant to human is Options:
  A) sulphur (IV) oxide
  B) carbon (IV) oxide
  C) nitrogen (II) oxide
  D) hydrogen sulphide
  Show Answer
  The correct answer is D .