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 1591: Which of the following reaction is endothermic? Options:
  A) C_(s) + O_2(g) → CO_2(g)
  B) CaO_(s) + H₂O_(l) → Ca(OH)_2(s)
  C) C_(s) + H₂O_(g) → CO_(g) + H_2(g)
  D) HCl_(aq) + NaOH_(aq) → NaCl_(aq) + H₂O_(l)
  Show Answer
  The correct answer is C .
• Question 1592:

  

  The diagram above represents an atom of

  Options:
  A) magnesium
  B) helium
  C) chlorine
  D) neon
  Show Answer
  The correct answer is A .
• Question 1593: Safety matches contain sulphur and? Options:
  A) potassium trioxochlorate (V)
  B) potassium trioxonitrate (V)
  C) charcoal
  D) phosphorus sulphide
  Show Answer
  The correct answer is D .
• Question 1594: In the purification of town water supply, alum is used principally to? Options:
  A) kill bacteria
  B) control the pH of water
  C) improve the taste of the water
  D) coagulate small pasrticles of mud
  Show Answer
  The correct answer is D .
• Question 1595: A stream of air was successively passed through three tubes X, Y and Z containing a concentrated aqueous solution of KOH, red hot copper powder and fused calcium chloride respectively. What was the composition of the gas emanating from tube Z? Options:
  A) CO₂ ad ithe inert gases
  B) N₂, CO₂ and the inert gases
  C) N₂ and the inert gases
  D) water vapour, N₂ and the inert gases
  Show Answer
  The correct answer is C .
• Question 1596: The noble gas, argon, is used for Options:
  A) electrical arc welding
  B) welding brass
  C) underwater welding
  D) steel-welding
  Show Answer
  The correct answer is A .
• Question 1597:

  Calculate the volume in cm³ of oxygen evolved as s.t.p. when a current of 5 A is passed through acidified water for 193s

  {F = 96500 Cmol^-1, Molar volume of a gas at s.t.p. = 22.4 dm³}

  Options:
  A) 224.000 dm³
  B) 0.056 dm³
  C) 0.224 dm³
  D) 56.000 dm³
  Show Answer
  The correct answer is B .
• Question 1598: In the reaction of oxygen with hydrogen to produce water, which of the following statements is true? Options:
  A) One atom of hydrogen reacts with two atoms of oxygen to give one molecule of water
  B) Two atoms of hydrogen react with two atoms of oxygen to give two molecules of water
  C) One molecule of oxygen reacts with one molecule of hydrogen to give two molecules of water
  D) One molecule of hydrogen reaccts with two molecules of oxygen to give three molecules of water
  E) One molecule of oxygen reacts with two molecules of hydrogen to give two molecules of water
  Show Answer
  The correct answer is E .
• Question 1599: If the relative molecular mass of an element is not a whole number, it can be deduced that the element is Options:
  A) naturally radioactive
  B) abundant in nature
  C) a transition metal
  D) an isotopic mixture
  Show Answer
  The correct answer is D .
• Question 1600: One mole of a hydrocarbon contains 48 g of carbon. If it vapour density is 28, the hydrocarbon is? Options:
  A) an alkane
  B) an alkene
  C) an alkyne
  D) aromatic (C = 12, H = 1)
  Show Answer
  The correct answer is B .