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?

  • A 10 and 10
  • B 9 and 9
  • C 11 and 9
  • D 9 and 11
jamb 1991chemistry

The correct answer is D. 9 and 11

X- means one excess electron, hence 9 protons while Y +/- means one deficit electron hence 11 protons X and Y = 9 and 11

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