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 161:

  Consider the reaction: A + 2B${}_{(g)}\rightleftharpoons$ 2C + D${}_{(g)}$ ($\mathrm{\Delta }$H = +ve)

  What will be the effect of decrease in temperature on the reaction?

  Options:
  A) Rate of backward reaction will increase
  B) The equilibrium constant will shift
  C) Rates of forward and backward reactions are not affected
  D) Rate of forward reaction will increase
  Show Answer
  The correct answer is A .
• Question 162: Coal fire should not be used in poorly ventilated rooms because ? Options:
  A) of the accumulation of CO₂ which causes dep sleep
  B) it is usually too hot
  C) of the acumulation of CO which causes suffocation
  D) it removes most most of the gases in the rooms
  Show Answer
  The correct answer is C .
• Question 163:

  The chlorinated alkane often used industrially to remove grease is?

  Options:
  A) Tetrachloromethane
  B) Chloromethane
  C) Trichloromethane
  D) Dichloromethane
  Show Answer
  The correct answer is A .
• Question 164:

  The heat of formation of ethene, C${}_2$H${}_4$ is 50 kJmol${}^{-1}$, and that of ethane, C${}_2$H${}_6$ is -82kJmol${}^{-1}$. Calculate the heat evolved in the process:

  C${}_2$H${}_4$ + H${}_2$ $\to$ C${}_2$H${}_6$

  Options:
  A) -122kJ
  B) -132kJ
  C) -88kJ
  D) -60kJ
  Show Answer
  The correct answer is B .
• Question 165: 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 166: Which of the following organic compounds is very soluble in water? Options:
  A) CH₃COOH
  B) C₂H₂
  C) C₂H₄
  D) CH₃COOC₂H₅
  Show Answer
  The correct answer is A .
• Question 167: The bond formed between two elements with electron configurations 1s² 2s² 2p⁶ 3s² and 1s² 2s² 2p⁴ is Options:
  A) metallic
  B) covalent
  C) dative
  D) ionic
  Show Answer
  The correct answer is D .
• Question 168: The energy value of petrol can be determined by Options:
  A) Bomb calorimeter
  B) Catalytic cracker
  C) Fractionating column
  D) Thermometer
  Show Answer
  The correct answer is C .
• Question 169:

  The sub-atomic particles located in the nucleus of an atomare?

  Options:
  A) neutron and proton
  B) proton and electron
  C) proton and ions
  D) neutron and electron
  Show Answer
  The correct answer is A .
• Question 170: The postulate of Dalton's atomic theory which still holds is that Options:
  A) atoms can neither be created nor destroyed
  B) the particles of the same element are exactly alike
  C) particles of different elements combine in simple whole number ratio
  D) all elemets are made of small indivisible particles
  Show Answer
  The correct answer is A .