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A metallic ion Z\(^{2+}\) with an inert gas structure contains 18 electrons. How many protons...

Chemistry
WAEC 2015

A metallic ion Z\(^{2+}\) with an inert gas structure contains 18 electrons. How many protons are contained in this ion?

  • A. 20
  • B. 18
  • C. 16
  • D. 2
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Correct Answer: Option A
Explanation

The number of electron would have been equal to number of proton if the atom were a neutral atom or represented as Z without Z\(^{2+}\). But because it is Z\(^{2+}\), carrying +2, meaning 2electrons were given out, therefore number of protons will be more than number electron by 2. i.e number of electron + 2 = 18 + 2 = 20. Therefore, the number of protons will be 20.


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