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 991: The Avogadro number of 24g of magnesium is the same as that of Options:
  A) 1g of hydrogen molecules
  B) 16g of oxygen molecules
  C) 32g of oxygen molecules
  D) 35.5g of chlorine molecules
  Show Answer
  The correct answer is C .
• Question 992: Tetraoxosulphate (VI) acid burns the skin by Options:
  A) Hydrolysis
  B) Hydration
  C) Heating
  D) Dehydration
  Show Answer
  The correct answer is D .
• Question 993:

  The cost of discharging 6.0g of a divalent metal, X from its salt is ₦12.00. What is the cost of discharging 9.0g of a trivalent metal, Y from its salt under the same condition?

  [X = 63, Y = 27, 1F = 96,500C]

  Options:
  A) N12.00
  B) N27.00
  C) N63.00
  D) N95.00
  Show Answer
  The correct answer is C .
• Question 994:

  The percentage of water of crystallization in ZnSO₄.7H₂O is

  [Zn = 65, S = 32, O = 1, H = 1]

  Options:
  A) 33%
  B) 44%
  C) 55%
  D) 87%
  Show Answer
  The correct answer is B .
• Question 995: Chlorine gas turns damp starch-iodide paper Options:
  A) pink
  B) colourless
  C) red
  D) dark blue
  Show Answer
  The correct answer is D .
• Question 996: The process that requires the use of hardwater in its operation is Options:
  A) Tanning
  B) Bottling
  C) Laundry
  D) Dyeing
  Show Answer
  The correct answer is B .
• Question 997: Methane is member of the homologous series called? Options:
  A) alkenes
  B) alcohols
  C) esters
  D) alkanes
  E) alkynes
  Show Answer
  The correct answer is D .
• Question 998:

  I. It has a varied composition from one place to another.

  II. It constituents can be separated by physical means.

  III. It contains unreactive noble gases

  Which of the above shows that air is a mixture?

  Options:
  A) I and II only
  B) II and III only
  C) I and III only
  D) I, II and III
  Show Answer
  The correct answer is A .
• Question 999:

  

  Use the above graph above to answer this question . CH₃-C = CH $\frac{Na}{liqN{H}_3}$> P, Compound P, in the above reaction, is

  Options:
  A) A
  B) B
  C) C
  D) D
  Show Answer
  The correct answer is B .
• Question 1000: NH_3(g) + HCl_(s) → NH ₄Cl _(s)The entropy change in the system above is Options:
  A) positive
  B) zero
  C) negative
  D) intermediate
  Show Answer
  The correct answer is C .