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 231: A property of a colloidal dispersion which a solution does not have is? Options:
  A) the Tyndall effect
  B) homogeneity
  C) osmotic pressure
  D) surface polarity
  Show Answer
  The correct answer is A .
• Question 232: A constituent common to bronze and solder is Options:
  A) lead
  B) silver
  C) copper
  D) tin
  Show Answer
  The correct answer is D .
• Question 233: A student prepares 0.5 M solution each of hydrochloric and ethanoic acids and then measured pH. The result would show that the? Options:
  A) pH values are equal
  B) HCI solution has a higher pH
  C) sum of the values is 14
  D) ethanoic acid solution has a higher pH
  Show Answer
  The correct answer is D .
• Question 234:

  Temp (°C)	25	35	45
  Time (seconds)	72	36	18

  The times taken for iodine to be liberated in the reaction between sodium thiosulphate and hydrochloric acid at various temperature are as follows. These results suggest that

  Options:
  A) for a 10^o rise in temperature, rate of reaction is double
  B) for a 10 ^o rise in temperature, rate of reaction is halved
  C) time taken for iodine to appear does not depend on temperature
  D) for a 10 ^o rise in temperature rate of reaction is tripled
  Show Answer
  The correct answer is A .
• Question 235:

  6AgNO_4(aq) + PH_3(g) + 3H₂O_(l) → 6Ag_(s) + H₃PO_3(g) + 6HNO_3(aq)

  In the above reaction, the reducing agent is

  Options:
  A) HNO_3(aq)
  B) H₂O_(l)
  C) PH_3(g)
  D) AgNO_3(aq)
  Show Answer
  The correct answer is C .
• Question 236: An example of aliphatic unsaturated hydrocarbon is Options:
  A) pentane
  B) butanol
  C) propene
  D) benzene
  Show Answer
  The correct answer is C .
• Question 237: The four classes of hydrocarbons are? Options:
  A) ethane, ethene, ethyne and benzene
  B) alkanes, alkenes, alkynes and aromatics
  C) alkanes, alkenes, alkynes and benzene
  D) methane, ethane , propane and butane
  Show Answer
  The correct answer is B .
• Question 238: Alkanals can be distinguished from alkanones by the reaction with Options:
  A) sudan lll stain
  B) starch iodide paper
  C) lithium tetrahydrido aluminate (lll)
  D) fehling's solution
  Show Answer
  The correct answer is D .
• Question 239: The reaction of carbide with water gives Options:
  A) ethyne
  B) ethene
  C) ethane
  D) ethanal
  Show Answer
  The correct answer is A .
• Question 240: The standard enthalpies of formation of CO_2(g), H₂O(g) and CO_(g) in kJ mol^- are -394, -242 and -110 respectively. What is the standard enthalpy change for the reaction CO_(g) + H_2(g)O → CO_2(g) + H_2(g)? Options:
  A) -42 KJ mol^-
  B) +42 KJ mol^-
  C) -262 KJ mol^-
  D) +262 KJ mol^-
  Show Answer
  The correct answer is A .