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 671:

  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 672: In the extraction of iron, which of the following reactions does NOT take place in the blast furnace? Options:
  A) CO₂ + C → 2CO
  B) 2Fe₂O₃ + 3C → 4Fe + 3CO₂
  C) Fe₂O₃ + 3C → 2Fe + 3CO₂
  D) CaCO₃ → CaO + CO₂
  E) CaO + SiO₂ → CaSiO₃
  Show Answer
  The correct answer is B .
• Question 673: In titration involving sodium hydroxide and dilute hydrochloric acid, where would you place the base? Options:
  A) in the beaker
  B) in the conical flask
  C) in a burette
  D) in the standard flask
  E) in the measuring cylinder
  Show Answer
  The correct answer is B .
• Question 674: 1.0 dm³ of distilled water was used to wash 2.0g of a precipitate of AgCl. If the solubility product of AgCl is 2.0 * 10^-10mol²dm^-6, what quantity of silver was lost in the process? Options:
  A) 2.029 * 10^-3mol dm^-3
  B) 1.414 * 10^-3mol dm^-3
  C) 2.029 * 10^-5mol dm^-3
  D) 1.414 * 10^-5mol dm^-3
  Show Answer
  The correct answer is D .
• Question 675: How many grams of bromine will be required to completely react with 10 g of propyne?(C = 12, H = 1, Br = 80) Options:
  A) 20 g
  B) 40 g
  C) 60 g
  D) 80 g
  Show Answer
  The correct answer is D .
• Question 676:

  CH₃COOH_(g) → H_4(g) + CO_2(g)

  The reaction above is

  Options:
  A) Carboxylation
  B) Decarboxylation
  C) Acidification
  D) Esterification
  Show Answer
  The correct answer is B .
• Question 677: Which of the following decreases when a given mass of gas is compressed to half its initial volume? Options:
  A) Average intermolecular distance
  B) Frequency of collisions
  C) Number of molecules present
  D) Atomic radius of each particle
  Show Answer
  The correct answer is A .
• Question 678: On recrystallization, 20g of magnesium tetraoxosuphate (IV) forms 41 g of magnesium tetraoxosulphate (IV) crystals, MgSO₄. yH₂O. The value of y is?(Mg = 24, S = 32, O = 16, H = 1) Options:
  A) 1
  B) 3
  C) 5
  D) 7
  Show Answer
  The correct answer is D .
• Question 679: Which of the following represents an aromatic compound? Options:
  A) C₆H₅OH
  B) C₆H₁₂
  C) C₆H₉OH
  D) C₆H₈
  Show Answer
  The correct answer is A .
• Question 680:

  

  Use the option above to answer this question. The structure of benzoic acid is

  Options:
  A) A
  B) B
  C) C
  D) D
  Show Answer
  The correct answer is D .