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 1281:

  MnO^-4_(aq) + Y + 5Fe²⁺_(aq) → Mn²⁺_(aq) + 5Fe²⁺_(aq) + 4H₂O_(l)
  In the equation above, Y is

  Options:
  A) 5H⁺_(aq)
  B) 4H⁺_(aq)
  C) 10H⁺_(aq)
  D) 8H⁺_(aq)
  Show Answer
  The correct answer is D .
• Question 1282: When plastics and packaging materials made from chloroethene are burnt in the open, the mixture of gases released into the atmosphere is most likely to contain? Options:
  A) ethane
  B) chlorine
  C) hydrogen chloride
  D) ethene
  Show Answer
  The correct answer is C .
• Question 1283: An example of a polysaccharides is? Options:
  A) —dextrose
  B) mannose
  C) glucose
  D) starch
  Show Answer
  The correct answer is D .
• Question 1284: 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 1285: In the periodic table, what is the property that decreases along the periodic and increases down the group? Options:
  A) Atomic number
  B) Electron affinity
  C) Ionization potential
  D) Atomic radius
  Show Answer
  The correct answer is D .
• Question 1286: In what respect will two dry samples of nitrogen gas differ from each other if sample 1 is prepared by completely removing CO₂ and O₂ from air, and sample 2 is prepared by passing purified nitrogen(i)oxide over heated copper? sample 1 is Options:
  A) purer than sample 2
  B) slightly denser than sample 2
  C) in all respects the same as sample 2
  D) colourless but sample 2 has a light brown colour
  E) slightly less reactive than sample 2
  Show Answer
  The correct answer is B .
• Question 1287: The oxidation states of chlorine in HOCL, HCLO₃ and HCLO₄ are respectively? Options:
  A) -1, +5, and +7
  B) -1, -5 and 7
  C) +1, +3 and +4
  D) +1, +5 and +7
  Show Answer
  The correct answer is D .
• Question 1288:

  The densities of two gases, X and Y, are 0.5 g dm^-3 and 2.0 dm^-3 respectively.

  What is the rate of diffusion of X relative to Y?

  Options:
  A) 0.1
  B) 0.5
  C) 2.0
  D) 4.0
  Show Answer
  The correct answer is C .
• Question 1289:

  Zn_(s) + CuSO_4(aq) $\to$ ZnSO_4(aq) + Cu_(s)

  In the reaction above, the oxidizing agent is

  Options:
  A) CuSO_4(aq)
  B) ZnSO_4(aq)
  C) Cu_(s)
  D) Zn_(s)
  Show Answer
  The correct answer is A .
• Question 1290:

  

  In the experiment above, Z can be

  Options:
  A) a solution of sodium dioxonitrate (lll) and ammonium chloride
  B) a solution of lead trioxnitrate (V)
  C) a solution of sodium trioxonitrate (V) and ammonium chloride
  D) concentrated tetraoxosulphate (VI) acid and sodium trioxonitrate (V)
  Show Answer
  The correct answer is C .