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 631: Three liquids X, Y and Z containing only hydrogen and carbon were burnt on a spoon. X and Y burnt with sooty flames while Z did not. Y is able to discharge the colour of bromine water whereas X and Z cannot. Which of the liquids would be aromatic in nature? Options:
  A) X and Z
  B) Y
  C) X
  D) Z
  Show Answer
  The correct answer is B .
• Question 632: Which of the following, in clear solution, forms a white precipitate when carbon (IV) oxide is bubbled into it for a short time? Options:
  A) KOH
  B) NaOH
  C) Ca(OH)₂
  D) AI(OH)₃
  Show Answer
  The correct answer is C .
• Question 633: In which of the following reactions does hydrogen peroxide act as a reducing agent? Options:
  A) H₂S + H₂O₂ $\to$ S + 2H₂O
  B) PbSO₃ + H₂O₂ $\to$ PbSO₄ + H₂O
  C) 2I+ 2H⁺ + H₂O₂ $\to$ I₂ + 2H₂O
  D) PbO₂ + 2HNO₃ + H₂O₂ $\to$ Pb(NO₃)₂ + 2H₂O + O₂
  E) SO₂ + H₂O₂ $\to$ H₂SO₄
  Show Answer
  The correct answer is D .
• Question 634:

  

  Which of the following is the correct order in the above diagram increasing boiling point, of the isomeric C₅H₁₂ compounds?

  Options:
  A) A
  B) B
  C) C
  D) D
  E) E
  Show Answer
  The correct answer is A .
• Question 635:

  NH_3(g) + HCl_(g) → NH₄Cl_(s)

  The entropy change in the system above is

  Options:
  A) negative
  B) indeterminate
  C) positive
  D) zero
  Show Answer
  The correct answer is A .
• Question 636: 5 block elements of the periodic table one made up of Options:
  A) groups 1, 2, 3
  B) groups 1, and 2
  C) group 3
  D) group 3 to 7
  Show Answer
  The correct answer is B .
• Question 637: ${}_{88}^{226}Ra$ → ${}_{86}^{x}Rn$ + alpha particle Options:
  A) 226
  B) 220
  C) 227
  D) 222
  Show Answer
  The correct answer is D .
• Question 638: Neutralization involves a reaction between H₃O⁺ and? Options:
  A) CI^-
  B) OH^-
  C) NO₃^-
  D) CO₃^2-
  Show Answer
  The correct answer is B .
• Question 639: Cathode rays causes an object placed behind a perforated anode to cast a shadow on the screen. This observation shows that the rays Options:
  A) are positively charged
  B) are negatively charged
  C) have mass
  D) travel in straight lines
  Show Answer
  The correct answer is D .
• Question 640: The soft solder used for welding and plumbing is alloy of Options:
  A) lead and tin
  B) iron and tin
  C) lead and zinc
  D) iron and zinc
  Show Answer
  The correct answer is A .