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JAMB Chemistry 1991 Question 10

Question 10

Atomic Structure

The ions X− and Y+ are isoelectronic, each containing a total of 10 electrons. How many protons are in the nuclei of the neutral atoms of X and Y respectively?

  1. A.10 and 10
  2. B.9 and 9
  3. C.11 and 9
  4. D.9 and 11
Show the answer and explanation

Answer: D (9 and 11)

Explanation

X− has one more electron than protons, so X has 9 protons. Y+ has one fewer electron than protons, so Y has 11.