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 1931:

  If the heat of combustion of hydrogen is -285.8kJ,

  What is the heat of formation of water?

  Options:
  A) +571.6 kJ
  B) -571.6 kJ
  C) -285.8 kJ
  D) +285.8 kJ
  Show Answer
  The correct answer is C .
• Question 1932: Moving from left to right across a period, the general rise in the first ionization energy can be attributed to the Options:
  A) decrease in nuclear charge
  B) increase in nuclear charge
  C) decrease in screening effect
  D) increase in screening effect
  Show Answer
  The correct answer is B .
• Question 1933: The carbon atoms on ethane are? Options:
  A) sp² hybridized
  B) sp³ hybridized
  C) sp²d hybridized
  D) sp hybridized
  Show Answer
  The correct answer is B .
• Question 1934:

  In the preparation of oxygen by heating KCIO, in the presence of MnO${}_2$ only moderate heat is needed because the catalyst acts by ${}_2$

  Options:
  A) lowering the pressure of the reaction
  B) increasing the surface area of the reaction
  C) increasing the rate of the reaction
  D) lowering the energy barrier of the reaction
  Show Answer
  The correct answer is D .
• Question 1935: The radioisotope used in industrial radiography for the rapid checking of faults in welds and casting is Options:
  A) Phosphorus-32
  B) Cobalt-60
  C) Carbon-14
  D) Iodine-131
  Show Answer
  The correct answer is B .
• Question 1936: Which of the following gases can be collected by the upward displacement of air? Options:
  A) NO
  B) H ₂
  C) NH₃
  D) Cl ₂
  Show Answer
  The correct answer is D .
• Question 1937:

  Which of the following factors does NOT affect the rate of a chemical reaction?

  Options:
  A) Concentration of reactants
  B) Presence of a catalyst
  C) Molecular weight of products
  D) Temperature
  Show Answer
  The correct answer is C .
• Question 1938: The allotropy of carbon used in the decolourization of sugar is Options:
  A) Graphite
  B) Soot
  C) Charcoal
  D) Lampblack
  Show Answer
  The correct answer is C .
• Question 1939:

  

  Use the option above to answer this question. The graph that describes a zero order reaction is

  Options:
  A) A
  B) B
  C) C
  D) D
  Show Answer
  The correct answer is B .
• Question 1940: If the rate of diffusion of oxygen gas is taken as 1, what will be rated of diffusion of methane whose relative molar mass is 16? Options:
  A) 2.0
  B) 1.8
  C) 1.4
  D) 1.0
  E) 0.5
  Show Answer
  The correct answer is C .