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 121:

  2H${}_2$ + O${}_2$ 2H${}_2$O

  From the equationabove, calculate the volume of unreacted oxygen gas if a mixture of 50cm${}^3$ of hydroden and 75cm${}^3$ of oxygen are involved

  Options:
  A) 85cm${}^3$
  B) 50cm${}^3$
  C) 125cm${}^3$
  D) 55cm${}^3$
  Show Answer
  The correct answer is B .
• Question 122:

  

  The IUPAC nomenclature of the structure is

  Options:
  A) 3-chloro-3-methylbutane
  B) 2,2,-dichloro-3-methylbutane
  C) 3-methylchlorobutane
  D) 2-chloro-2-methylbutane
  Show Answer
  The correct answer is D .
• Question 123: In the manufacture of iron in the blast furnace, iron (lll) oxide is mixed with coke and limestone, and different reactions occur in the process. Which of the following statements is true with respect to these reactions? Options:
  A) the coke is a powerful reducing agent and easily converts the iron oxide to iron
  B) the calcuim carbonate reacts with SiO₂ an earthly impurity in the ore, to from calcuim silicate
  C) the coke will react with the iron produced to form steel
  D) all the carbondioxide required in the process comes from the decomposition of the calcium carbonate
  E) the calcium carbonate decomposes to give calcium oxide, which then forms calcium silicate with the earthly impurity
  Show Answer
  The correct answer is E .
• Question 124: A certain industrial process is represented by the chemical equation 2A_(g) + B_(g) $\to$ C_(g) + 3D_(g) $\mathrm{\Delta }$H = X kJmol^-1. Which of the following conditions will favour the yield of the products? Options:
  A) increase in temperature, decrease in pressure
  B) increase in temperature, increase in pressure
  C) decrease in temperature,increase in pressure
  D) decrease in temperature, decrease in pressure
  E) constant in temperature, increase in pressure
  Show Answer
  The correct answer is A .
• Question 125: The radio active radiation used in studying the arrangement of particles in giant organic molecules is Options:
  A) $\gamma$- rays
  B) $\alpha$- particles
  C) X-rays
  D) $\beta$ - particles
  Show Answer
  The correct answer is C .
• Question 126:

  

  From the diagram above the mass of crystals deposited when 1 dm ³ of a saturated solution of NaCl is cooled from 80^oC to 60^oC is

  [Na = 23, Cl = 35.5]

  Options:
  A) 117.00 g
  B) 58.50 g
  C) 11.70 g
  D) 5.85 g
  Show Answer
  The correct answer is A .
• Question 127: The electronic configuration of an elements is 1s²2s²2p⁶3s²3p³. How many unpaired electrons are there in the element? Options:
  A) 5
  B) 4
  C) 3
  D) 2
  Show Answer
  The correct answer is C .
• Question 128: The constituent of air that acts as a diluent is Options:
  A) nitrogen
  B) carbon (IV) oxide
  C) noble gases
  D) oxygen
  Show Answer
  The correct answer is A .
• Question 129: A gas that turns a filter paper previously soaked in lead ethanoate solution black is? Options:
  A) hyrogen chloride
  B) hydrogen sulphide
  C) sulphur (IV) oxide
  D) sulphur (VI) oxide
  Show Answer
  The correct answer is B .
• Question 130:

  

  In the electrolysis of aqueous solution of K₂SO ₄ in the above cell, which species migrate to the anode?

  Options:
  A) SO^2-OH ^-
  B) K ⁺ and SO ₄^2-
  C) OH and HO
  D) H₃O ⁺ and K
  Show Answer
  The correct answer is A .