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 991:

  Which of the following is a primary constituent of crude oil?

  Options:
  A) Pentane
  B) Ethanol
  C) Heptane
  D) Methane
  Show Answer
  The correct answer is D .
• Question 992: Which of the following is an example of a mixture? Options:
  A) Common salt
  B) Blood
  C) Sand
  D) Washing soda
  Show Answer
  The correct answer is B .
• Question 993:

  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 994: A certain volume of gas at 298k is heated such that its volume and pressure are now four times the original values. What is the new temperature? Options:
  A) 18.6k
  B) 100.0k
  C) 298.0k
  D) 1192.0k
  E) 4768.0k
  Show Answer
  The correct answer is E .
• Question 995:

  2SO_2(g) + O_2(g) $⟺$2SO_3(g)

  $△H=-395.7kJmo{l}^{-1}$

  In the reaction above, the concentration of 2SO_3(g) can be in creased by

  Options:
  A) decreasing the pressure
  B) decreasing the temperature
  C) the addition of catalyst
  D) increasing the temperature
  Show Answer
  The correct answer is B .
• Question 996: Which is the temperature of a given mass of a gas initially at 0°C and 9 atm, if the pressure is reduced to 3 atm at constant volume? Options:
  A) 91K
  B) 182K
  C) 273K
  D) 819K
  Show Answer
  The correct answer is A .
• Question 997: Given the mean atomic mass of chlorine prepared in the laboratory to be 35.5 and assuming that chlorine contains two isotopes of mass number 35 nad 37, what is the percentage composition of the isotope of mass number 35? Options:
  A) 20
  B) 25
  C) 50
  D) 75
  E) 90
  Show Answer
  The correct answer is D .
• Question 998: In the industrial production of hydrogen from natural gas, carbon (IV) oxide produced along with the hydrogen is removed by? Options:
  A) washing under pressure
  B) passing the mixture into lime water
  C) using ammoniacal copper (l) chloride
  D) drying over phoshorus (V) oxide
  Show Answer
  The correct answer is C .
• Question 999: The hybridization of the carbon atom in ethyne is Options:
  A) sp ⁴
  B) sp ³
  C) sp²
  D) sp
  E) s
  Show Answer
  The correct answer is D .
• Question 1000:

  From the graph above, it may be concluded that

  Options:
  A) AgNO${}_3$ is probably not soluble at 1100
  B) NaCl is insoluble in water
  C) Pb(NO${}_3$)${}_2$ is more soluble than KCIO${}_3$
  D) The solubility of KCIO${}_3$ exceeds that of NaCl at all temperature
  Show Answer
  The correct answer is C .