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 701:

  N₂O_4(g) ↔ 2NO_2(g) ΔH = +ve

  In the reaction above, an increase in temperature will

  Options:
  A) increase the value of the equilibrium constant
  B) decreases the value of the equilibrium constant
  C) increase in the reactant production
  D) shift the equilibrium to the left
  Show Answer
  The correct answer is A .
• Question 702: How many structural isomers can be drawn for the non-cyclic alkanol with molecular formula C ₄H₁₀O? Options:
  A) 1
  B) 2
  C) 3
  D) 4
  Show Answer
  The correct answer is D .
• Question 703: A mixture contains 20cm³ of hydrogen, 35cm³ of oxygen, 15cm³ of carbon monoxide and 10cm³ of nitrogen at S.T.P. Which of the following gives the mole fraction of hydrogen in this mixture? Options:
  A) 0.02
  B) 0.16
  C) 0.20
  D) 0.25
  E) 20
  Show Answer
  The correct answer is D .
• Question 704: Which of the following would support the conclusion that a solid sample is a mixture? Options:
  A) the solid can be ground to a fine powder
  B) the density of the solid is 2.25 g dm³
  C) the solid has a melting range of 300^oC to 375^oC
  D) the solid absorbs moisture from the atmosphere
  Show Answer
  The correct answer is C .
• Question 705: A few drops of NaOH solution was added to an unknown salt forming a white precipitate which is insoluble in excess solution. The cation likely present is Options:
  A) Zn²⁺
  B) Pb²⁺
  C) Ca²⁺
  D) Al³⁺
  Show Answer
  The correct answer is C .
• Question 706:

  

  Use the figure above to answer this question. Which of the following compounds is an isomer of the compound

  Options:
  A) A
  B) B
  C) C
  D) D
  Show Answer
  The correct answer is D .
• Question 707: If sulphur (IV) oxide and methane are released simultaneously at the opposite ends of a narrow tube, the rates of diffusion Rso₂ and Rch₄ will be in the ratio? (S = 32, O = 16, C = 12, H = 1) Options:
  A) 4:1
  B) 2:1
  C) 1:2
  D) 1:4
  Show Answer
  The correct answer is C .
• Question 708: A form of carbon used for absorbing poisonous gases and purification of noble gases is Options:
  A) wood charcoal
  B) animal charcoal
  C) carbon fibres
  D) carbon black
  Show Answer
  The correct answer is A .
• Question 709: The relationship between the velocity (U) of gas molecules and their relative molecular mass (M) is shown by the equation Options:
  A) U = (kM)$\frac{1}{2}$
  B) U = (kM)²
  C) U = $\sqrt{k}m$
  D) U = ($\frac{k}{m}$)${}^{\frac{1}{2}}$
  Show Answer
  The correct answer is C .
• Question 710: The best treatment for a student who accidentally poured concentrated tetraoxosulphate (VI) acid on his skin in the laboratory is to wash the skin with? Options:
  A) cold water
  B) sodium hydroxide solution
  C) iodine solution
  D) sodium trioxocarbonate (IV) solution
  Show Answer
  The correct answer is B .