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 891: Which of the following statements applies during the electroysis of sodium hydroxide sodium hydroxide solution using platinum electrodes? Options:
  A) Na⁺ ions are discharged at the cathode
  B) Hydrogen ions are discharged at the anode
  C) the concentration of sodium hydroxide decrease at both electrode compartments
  D) the concentration of sodium hydroxide increases at the cathode only
  E) the concentration of sodium hydroxide increases at the anode only
  Show Answer
  The correct answer is D .
• Question 892: Tin is unaffected by air at ordinary temperature due to its Options:
  A) Low melting point
  B) Weak electropositive character
  C) High boiling point
  D) White lustrous appearance
  Show Answer
  The correct answer is A .
• Question 893:

  Benzene can be converted to its derivative toluene by the addition of a methyl group. The reaction is an example of

  Options:
  A) Nucleophilic substitution
  B) Elimination reaction
  C) Electrophilic substitution
  D) Addition reaction
  Show Answer
  The correct answer is C .
• Question 894:

  A 'breath test' used by traffic police to check drunken driving uses?

  Options:
  A) Tumeric on filter paper
  B) Silica gel coated with saliva nitrate
  C) Potassium permanganate-sulphuric acid
  D) Potassium dichromatic-sulphuric acid
  Show Answer
  The correct answer is D .
• Question 895:

  A metal M displaces zinc from ZnCl, solution, solution

  This shows that

  Options:
  A) electrons flow from zinc to M
  B) M is more electropositive than zinc
  C) M is more electonegative than zinc
  D) zinc is more electropositive than M
  Show Answer
  The correct answer is B .
• Question 896: What is the decrease in volume of air when pyrogallol is shaken with 30.00cm³ of air ? Options:
  A) 15.00cm³
  B) 6.30cm³
  C) 0.63cm³
  D) 0.06cm³
  Show Answer
  The correct answer is B .
• Question 897:

  An element, X, forms a volatile hydride XH₃ with a vapour density of 17.0. The relative atomic mass of X is?

  (H = 1)

  Options:
  A) 34.0
  B) 31.0
  C) 20.0
  D) 14.0
  Show Answer
  The correct answer is B .
• Question 898: Which of the following chloride would exhibit the least ionic character? Options:
  A) MgCl₂
  B) CaCl₂
  C) LiCl
  D) AlCl₃
  Show Answer
  The correct answer is D .
• Question 899: The number of hydrogen ions in 4.9 g of tetraoxosulphate (IV) acid is?(S = 32, O =16, H = 1, Na = 6.02 x 10₂₃ Options:
  A) 3.01 x 10₂₂
  B) 6.02 x 10₂₂
  C) 3.01 x 10₂₃
  D) 6.01 x 10₂₃
  Show Answer
  The correct answer is B .
• Question 900:

  When a substance is oxidized, it

  Options:
  A) Loses electrons
  B) Gains oxygen atoms
  C) Gains electrons
  D) Loses protons (H+ ions)
  Show Answer
  The correct answer is A .