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Sunday, 14 June 2026
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Chemistry Past Questions and Answers

Jamb 1985 Chemistry Questions

Question 21:
Which of the following compounds is NOT the correct product formed when the parent metals is heated in air?
  • A Calcium oxide (CaO)
  • B Sodium oxide (Na<sub style='font-size: smaller;'>2</sub>O)
  • C Copper (ll) oxide (CuO)
  • D Tri-iron tetroxide (Fe<sub style='font-size: smaller;'>3</sub>O<sub style='font-size: smaller;'>4</sub>)
  • E Aluminium oxide (Al<sub style='font-size: smaller;'>2</sub>O<sub style='font-size: smaller;'>3</sub>)
View Answer & Explanation
Question 22:
The atomic number of an element whose cation, X2+, has the ground state electronic configuration 1s22s22p63s22p6 is?
  • A 16
  • B 18
  • C 20
  • D 22
  • E 24
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Question 23:
When marble is heated to about 1473 K, another white solid is obtained which reacts vigorously with water to give an alkaline solution. The solution contains?
  • A NaOH
  • B KOH
  • C Mg(OH)<sub style='font-size: smaller;'>2</sub>
  • D Zn(OH)<sub style='font-size: smaller;'>2</sub>
  • E Ca(OH)<sub style='font-size: smaller;'>2</sub>
View Answer & Explanation
Question 24:
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 25:
The process involved in the conversion of an oil into margarine is known as?
  • A Hydrogenation
  • B Condensation
  • C Pyrolysis
  • D Dehydration
  • E Cracking
View Answer & Explanation