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 1791: Fe₂O_3(s) + 2Al_(s) → Al₂O₃ + 2Fe_(s) If the heats of formation of Al₂O₃ and Fe₂O₃ are - 1670 kj mol^-1 and - 822 kj mol^-1 respectively, the enthalpy change in kj for the reaction is ? Options:
  A) +2492
  B) +848
  C) -848
  D) -2492
  Show Answer
  The correct answer is C .
• Question 1792: The scale of a chemical balance is made of iron plate and coated with copper electrolytically because Options:
  A) iron is less susceptible to corrosion than copper
  B) copper is twice as less susceptitible to corrosion as iron
  C) copper is less susceptible to corrosion than iron
  D) copper and iron are equally susceptible to corrosion
  Show Answer
  The correct answer is C .
• Question 1793: The entropy and enthalpy of a system are a measure of Options:
  A) degree of disorderlinesss and heat content respectively
  B) heat content and degree of disorderliness respectively
  C) heat content of a system only
  D) degree of disorderliness only
  Show Answer
  The correct answer is A .
• Question 1794:

  

  The figure above shows the electrolysis of molten sodium chloride. Z is the

  Options:
  A) anode where the Cl${}^{-}$ ions are oxidized
  B) cathode where the Cl${}^{-}$ ions are reduced
  C) anode where the Na${}^{+}$ ions are reduced
  D) cathode where the Na${}^{+}$ ions are oxidized
  Show Answer
  The correct answer is A .
• Question 1795:

  

  Use the following option above to answer this question. Which of the following compounds in solution will turn red litmus paper blue?

  Options:
  A) A
  B) B
  C) C
  D) D
  Show Answer
  The correct answer is C .
• Question 1796: When H₂S is passed into a solution of iron (III) chloride, the solution turns Options:
  A) Pale green
  B) Pale red
  C) Brown
  D) Colourless
  Show Answer
  The correct answer is A .
• Question 1797: The function of sulphur during vulcanization rubber is to? Options:
  A) act as catalyst for the polymerization of rubber molecules
  B) convert rubber from thermosetting to thermo plastics polymer
  C) from chains which bind rubber molecules together
  D) break down rubber polyer
  E) shorten the chain length of rubber polyer
  Show Answer
  The correct answer is C .
• Question 1798:

  

  The diagram above represents the formation of

  Options:
  A) a metallic bond
  B) an electrovalent bond
  C) a covalent bond
  D) a coordinate covalent bond
  Show Answer
  The correct answer is C .
• Question 1799:

  Consider the reaction

  A${}_{(s)}$ + 2B${}_{(g)}$ → 2C${}_{(aq)}$ + D${}_{(g)}$

  What will be the effect of a decrease in pressure on the reaction?

  Options:
  A) the equilibrium will shift
  B) rate of forward reaction will increase
  C) rate of backward reaction will increase
  D) rates of forward and backward reaction are not affected
  Show Answer
  The correct answer is B .
• Question 1800: A certain industrial process is represented by the chemical equation 2A_(g) + B_(g) $\to$ C_(g) + 3D_(g) $\mathrm{\Delta }$H = X kJmol^-1. Which of the following conditions will favour the yield of the products? Options:
  A) increase in temperature, decrease in pressure
  B) increase in temperature, increase in pressure
  C) decrease in temperature,increase in pressure
  D) decrease in temperature, decrease in pressure
  E) constant in temperature, increase in pressure
  Show Answer
  The correct answer is A .