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 86:
In the experiment, which of the following observations would suggest that a solid sample is a mixture? The
  • A Solid can be ground to a fine powder
  • B Density of the solid is 2.25gdm<sup style='font-size: smaller;'>-3</sup>
  • C Solid begins to melt at 573k but is not completely melted until 648k
  • D Solid absorbs moisture from the atmosphere and turns into liquid
  • E Solid melts at 300k
View Answer & Explanation
Question 87:
3.0g of a mixture of potassium carbonate and potassium chloride were dissolved in a 25cm3 of this solution required required 40.00cm3 of 0.1M HCl for neutralization. What is the percentage by weight of K2CO3 in the mixture. (K = 39, O = 16, C = 12)
  • A 60
  • B 72
  • C 82
  • D 89
  • E 92
View Answer & Explanation
Question 88:
Some properties of chemical substances are mentioned below... i. sour taste ii. slippery touch iii. yields alkaline gas with ammonium salt iv. has pH less than 7 v. turns phenolphthalein pink.
Which of the above are NOT typical properties of alkalis?
  • A I, iv and v
  • B Iv and v
  • C I and iv
  • D Ii and v
  • E Ii, iii and iv
View Answer & Explanation
Question 89:
Which of the following solutions will conduct the least amount of electricity?
  • A 2.00 M aqueous solution of NaOH
  • B 0.01 M aqueous solution of NaOH
  • C 0.01 M aqueous solution of hexanoic acid
  • D 0.01 M aqueous solution of sugar
View Answer & Explanation
Question 90:
A substance Z reacts with NaOH to give salt and water only. When Z is treated with dilute HCl, a gas is evolved which gives a yellow suspension on passing into concentrated H2SO4. Substance Z is?
  • A NaHS
  • B Na<sub style='font-size: smaller;'>2</sub>SO<sub style='font-size: smaller;'>3</sub>
  • C Na<sub style='font-size: smaller;'>2</sub>S
  • D NaHSO<sub style='font-size: smaller;'>3</sub>
View Answer & Explanation