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 381: The oxidation number of boron in NaBH ₄ is Options:
  A) -3
  B) -1
  C) +1
  D) +3
  Show Answer
  The correct answer is D .
• Question 382:

  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 383: Equal moles of ethyne and hydrogen iodide react to give Options:
  A) CH₂ = CH₂
  B) CH₂ - CHI
  C) CH₃ - CI
  D) CH₂ = CHI
  Show Answer
  The correct answer is D .
• Question 384:

  The electronic configuration of element Z is 1s${}^2$ 2s${}^2$ 2p${}^6$ 3s${}^2$ 3p${}^1$. What is the formula of the compound formed between Z and tetraoxosulphate (VI) ion.

  Options:
  A) Z${}_3$(SO${}_4$)${}_2$
  B) ZSO${}_4$
  C) Z${}_2$ SO${}_4$
  D) Z${}_2$(SO${}_4$)${}_3$
  Show Answer
  The correct answer is D .
• Question 385:

  When chlorine water is exposed to bright sunlight, the following products are formed

  Options:
  A) HCl${}_{(aq)}$ and Cl${}_2$
  B) HOCl${}_{(aq)}$ and Cl${}_2$
  C) HCl${}_{(aq)}$ and O${}_2$
  D) HOCl${}_{(aq)}$ and O${}_2$
  Show Answer
  The correct answer is C .
• Question 386: Which of the following pollutants is associated with brain damage? Options:
  A) Carbon (ll) oxide
  B) Radioactive fallout
  C) Biodegradable waste
  D) Sulphus (lV) oxide
  Show Answer
  The correct answer is A .
• Question 387:

  L . Evaporation. ll. Sublimation. lll. Diffusion. IV. Brownian motion.

  Which of the above can correctly be listed as evidences for the particulate nature of matter?

  Options:
  A) I and lll only
  B) ll and lV only
  C) l, ll and lll only
  D) l, ll, lll and lV
  Show Answer
  The correct answer is D .
• Question 388:

  

  The I.U.P.A.C name for the compound is

  Options:
  A) isopropylethene
  B) acetylene
  C) 3- methylbutane
  D) 2-methylbutane
  E) 5-methylpentane
  Show Answer
  The correct answer is D .
• Question 389: Which of the following alloys contain iron? Options:
  A) Duralumin and steel
  B) Brass and bronze
  C) Steel and permalloy
  D) Soft solder and duralumin
  Show Answer
  The correct answer is C .
• Question 390:

  What happens to the position of equilibrium, if a reversible exothermic reaction is subjected to a decrease in temperature?

  Options:
  A) The position of equilibrium shifts to the left
  B) The position of equilibrium shifts to the right.
  C) The position of equilibrium remains unchanged
  D) The reaction stops
  Show Answer
  The correct answer is B .