Search SchoolNGR

Tuesday, 16 June 2026
Register . Login

Chemistry Past Questions and Answers

Topic: Separation of mixtures and purification of chemical substances

Jamb Chemistry Questions - Separation of mixtures and purification of chemical substances

Question 81:
Solid sodium hydroxide on exposure to air absorbs a gas and ultimately gives another alkaline substance with the molecular formula?
  • A NaOH.H<sub style='font-size: smaller;'>2</sub>O
  • B NaOH.N<sub style='font-size: smaller;'>2</sub>
  • C Na<sub style='font-size: smaller;'>2</sub>CO<sub style='font-size: smaller;'>3</sub>O
  • D NaHCO<sub style='font-size: smaller;'>3</sub>
  • E NaNO<sub style='font-size: smaller;'>3</sub>O
View Answer & Explanation
Question 82:
Which of the following substances is the most abundant in the universe?
  • A Carbon
  • B Air
  • C Water
  • D Oxygen
  • E Hydrogen
View Answer & Explanation
Question 83:
Addition of dilute hydrochloride acid to an aqueous solution of a crystalline salt yield a yellow precipitate and a gas which turned dichromate paper green. The crystalline salt was probably?
  • A Na<sub style='font-size: smaller;'>2</sub>SO<sub style='font-size: smaller;'>4</sub>
  • B Na<sub style='font-size: smaller;'>2</sub>S
  • C Na<sub style='font-size: smaller;'>2</sub>S<sub style='font-size: smaller;'>2</sub>O<sub style='font-size: smaller;'>3</sub>.5H<sub style='font-size: smaller;'>2</sub>O
  • D Na<sub style='font-size: smaller;'>2</sub>CO<sub style='font-size: smaller;'>3</sub>
  • E NaHCO<sub style='font-size: smaller;'>3</sub>
View Answer & Explanation
Question 84:
Use the following option above to answer this question. Which of the following is the functional group of carboxylic acids?
  • A A
  • B B
  • C C
  • D D
  • E E
View Answer & Explanation
Question 85:
0.499g 0f CuSO4.xH2O when heated to constant weight gave a residue of 0.346g. the value of x is? (Cu = 63.5, S = 32.0, O = 16, H = 1)
  • A 0.5
  • B 2.0
  • C 3.0
  • D 4.0
  • E 5.0
View Answer & Explanation