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 781:

  If the cost of electricity required to discharge 10g of an ion X${}^{3+}$ is N20.00, how much would it cost to discharge 6g of ion Y${}^{2+}$?

  [1 faraday = 96,500C, atomic masses are X = 27, Y = 24]

  Options:
  A) N10.00
  B) N6.00
  C) N20.00
  D) N9.00
  Show Answer
  The correct answer is D .
• Question 782:

  The boiling of fat and aqueous caustic soda is referred to as

  Options:
  A) hydrolysis
  B) esterification
  C) acidification
  D) saponification
  Show Answer
  The correct answer is D .
• Question 783:

  

  Carbon (ll) oxide may be collected as shown above because it

  Options:
  A) is heavier than air
  B) is less dense than air
  C) is insoluble in water
  D) burns in oxygen to form carbon (IV) oxide
  Show Answer
  The correct answer is C .
• Question 784: When sodium hydroxide is heated with ammonium tetraoxosulphate (IV), the gas given off may be collected by? Options:
  A) bubbling it through concentrated H₂SO₂
  B) bubbling it through water and then passing it through calcium oxide
  C) passing it directly through calcium oxide
  D) passing it directly through calcium chloride
  Show Answer
  The correct answer is C .
• Question 785:

  The mass number of a nucleus is?

  Options:
  A) Always less than its atomic number
  B) The sum of the number of protons and neutrons present in the nucleus
  C) Always more than the atomic weight
  D) A fraction
  Show Answer
  The correct answer is B .
• Question 786:

  10g of a solid is in equilibrium with its own vapour.

  When 1 g of a small amount of solid is added, the vapour pressure?

  Options:
  A) remains the same
  B) drops
  C) increases by 1%
  D) increases by 99%
  Show Answer
  The correct answer is B .
• Question 787:

  

  In the experiment above, X could be a solution of

  Options:
  A) sodium trioxonitrate (V) and ammonium chloride
  B) sodium trioxonitrate (lll) and ammonium chloride
  C) lead (ll) trioxonitrate (V) and copper turnings
  D) potassium trioxonitrate (V) and copper turnings
  Show Answer
  The correct answer is B .
• Question 788:

  

  In the diagram above, R is a mixture of

  Options:
  A) potassium tetraxochlorate (VII) and concentrated H₂SO₄
  B) potassium trioxochlorate (V) and concentrated H₂SO₄
  C) potassium tetratoxomanganate (VII) and concentrated HCI
  D) manganes (IV) oxide and concentrated HCI
  Show Answer
  The correct answer is D .
• Question 789:

  What is the concentration of a solution containing 2g of NaOH in 100cm3 of solution? [Na = 23, O =16, H = 1]

  Options:
  A) 0.40 moldm${}^{-3}$
  B) 0.50 moldm${}^{-3}$
  C) 0.05 moldm${}^{-3}$
  D) 0.30 moldm${}^{-3}$
  Show Answer
  The correct answer is B .
• Question 790: Oxidation is the process of? Options:
  A) gain of electrons
  B) loss of electrons
  C) gain of hydrogen
  D) loss of oxygen
  E) addition of an electropositive element to a substance
  Show Answer
  The correct answer is B .