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 1541:

  

  In the solubility curve above, water at 98^oC is saturated with KCL and KCIO₃ What is the percentage of KCL impurity in the crystals formed when the solution is cooled to 30 ^oC?

  Options:
  A) 51.5
  B) 45.5
  C) 34.5
  D) 26.5
  Show Answer
  The correct answer is C .
• Question 1542: The bleaching action of chlorine gas is effective due to the presence of Options:
  A) hydrogen chloride
  B) water
  C) air
  D) oxygen
  Show Answer
  The correct answer is B .
• Question 1543: An amphoteric oxide is an? Options:
  A) amorphous oxide of a metal
  B) amorphous oxide of a non-mental
  C) oxide that is insoluble in water
  D) oxide that behaves both as a base as well as an acid
  E) oxide that loses its oxygen on sublimation
  Show Answer
  The correct answer is D .
• Question 1544:

  A certain hydrocarbon on complete combustion at s.t.p produced 89.6dm${}^3$ of CO${}_2$ and 54g of water. The hydrocarbon should be

  Options:
  A) C${}_6$H${}_6$
  B) C${}_4$H${}_{10}$
  C) C${}_5$H${}_{10}$
  D) C${}_4$H${}_6$
  Show Answer
  The correct answer is D .
• Question 1545: Geometric isomerism can exist in Options:
  A) hex-3-ene
  B) hexane
  C) prop-l-ene
  D) 3-methyl but -l-ene
  Show Answer
  The correct answer is A .
• Question 1546: ¹⁴₇N + X → ¹⁷₈O + ¹₁ H. In the above reaction, X is a? Options:
  A) neutron
  B) helium atom
  C) litgium atom
  D) deuterium atom
  Show Answer
  The correct answer is B .
• Question 1547: The industrial preparation of hydrogen gas from water gas is referred to as Options:
  A) Bosch process
  B) Contact process
  C) Haber process
  D) Bayer Process
  Show Answer
  The correct answer is A .
• Question 1548: When glowing splint is inserted into the mouth of a jar containing a gas, the splint is extinguished. The gas gives a white precipitate when passing into barium hydroxide. The gas is? Options:
  A) methane
  B) hydrogen chloride
  C) hydrogen
  D) nitrogen
  E) carbondioxide
  Show Answer
  The correct answer is E .
• Question 1549:

  The reaction $2H_{2}S+S{O}_2\to 3S+2H_{2}O$ is

  Options:
  A) not a redox reaction because there is no oxidant in the reaction
  B) not a redox reaction because there is no reductant in the reaction
  C) a redox reaction in which H${}_2$S is the oxidant and SO${}_2$ is the reductant
  D) a redox reaction in which SO${}_2$ is the oxidant and H${}_2$S is the reductant
  Show Answer
  The correct answer is D .
• Question 1550: If the change in free energy of a system is -899 Jmol^-1 and the entropy change is 10Jmol^-1k^-1 at 250C, calculate the enthalpy change. Options:
  A) +2081 Jmol^-1
  B) -2081 Jmol^-1
  C) -649 Jmol^-1
  D) +649 Jmol^-1
  Show Answer
  The correct answer is A .