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 1881:

  In the reactions

  (I) H₂ (g) + 1/2O₂(g) → H₂O(l); ∆H = -286 KJ

  (II) C(s) + O₂g) → CO₂ (g); ∆H = -406 KJ the equations imply that

  Options:
  A) more heat is absorbed in (l)
  B) more heat is absorbed in (ll)
  C) less heat is evolved in (l)
  D) reaction (ll) proceeds faster than (l)
  E) reaction (l) proceeds faster than (ll)
  Show Answer
  The correct answer is C .
• Question 1882: The flame used by welders in cutting metals is Options:
  A) butane gas flame
  B) acetylene flame
  C) kerosene flame
  D) oxy-acetylene flame
  E) oxygen flame
  Show Answer
  The correct answer is D .
• Question 1883: What is discharged at the cathode during the electrolysis of copper (ll) tetraoxosulphate (VI) solution? Options:
  A) Cu ²⁺ only
  B) H + only
  C) Cu ²⁺ and H
  D) Cu ²⁺ and SO ^2-
  Show Answer
  The correct answer is A .
• Question 1884: A given mass of gas occupies 2 dm³ at 300k. At what temperature will its volume be doubled keeping the pressure constant? Options:
  A) 400k
  B) 480k
  C) 550k
  D) 600k
  Show Answer
  The correct answer is D .
• Question 1885: Which of the following statements is FALSE about isotopes of the same element? Options:
  A) They have the same number of electrons in their outermost shells
  B) They have different atomic masses
  C) They have the same atomic number and the number of electrons
  D) They have the same atomic number but different umber of elelctrons
  Show Answer
  The correct answer is D .
• Question 1886:

  Which of the following is an example of an endothermic reaction?

  Options:
  A) Combustion of propane (C${}_3$H${}_8$) to produce carbon dioxide (CO${}_2$) and water (H${}_2$O).
  B) Burning of methane (CH${}_4$) in the presence of oxygen
  C) Formation of table salt (NaCl) from sodium (Na) and chlorine (Cl${}_2$).
  D) Decomposition of hydrogen peroxide (H${}_2$O${}_2$) into water (H${}_2$O) and oxygen (O${}_2$).
  Show Answer
  The correct answer is D .
• Question 1887: The product formed at the the cathode during the electrolysis of sodium chloride solution with carbon electrodes is? Options:
  A) sodium
  B) chlorine
  C) hydrogen
  D) sodium hydroxide
  E) oxygen
  Show Answer
  The correct answer is C .
• Question 1888:

  A concentrated solution containing H⁺, Cu²⁺, OH^- and Cl^- was electrolyzed using platinum electrodes.

  The ion that will be discharged at the cathode is

  Options:
  A) Cu²⁺
  B) Cl^-
  C) H⁺
  D) OH^-
  Show Answer
  The correct answer is A .
• Question 1889:

  

  Which of the curves shown in the figure given represents the relationships between the volume(V) and pressure(P) of an ideal gas at constant temperature?

  Options:
  A) 1
  B) 2
  C) 3
  D) 4
  E) 1 and 3
  Show Answer
  The correct answer is C .
• Question 1890: Bronze is preferred to copper in the making of medals because it Options:
  A) is stronger
  B) can withstand low temperature
  C) is lighter
  D) has low tensile strength
  Show Answer
  The correct answer is A .