Question

which of the following species has the same number of electron as well as penultimate shell.
A) mg2+
b) O2-
c) f-
d) Ca2+​

Answer 1

Answer:

Penultimate shell is the shell just before the outermost shell.

In Mg^+2 the electronic configuration is 2,8

In O^2− the electronic configuration is 2,8

In F− the electronic configuration is 2,8

In Ca^+2 the electronic configuration is 2,8,8

Hence, in calcium cation the number of electrons in the outermost shell is same as in penultimate Shell.

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