JEE MAIN - Chemistry (2003 - No. 57)
Which one of the following groupings represents a collection of isoelectronic species? (At. nos. : Cs : 55, Br : 35)
N3-, F-, Na+
Be, Al3+, Cl-
Ca2+, Cs+, Br
Na+, Ca2+, Mg2+
Explanation
Isoelectronic means those species whose electron number are same.
$$\therefore$$ N3-, F-, Na+
| Species | Atomic Number | Electron Number |
|---|---|---|
| N3- | 7 | 7 + 3 = 10 |
| F- | 9 | 9 + 1 = 10 |
| Na+ | 11 | 11 - 1 = 10 |
| Be | 4 | 4 |
| Al3+ | 13 | 13 - 3 = 10 |
| Cl- | 17 | 17 + 1 = 8 |
| Ca2+ | 20 | 20 - 2 = 18 |
| Cs+ | 55 | 55 - 1 = 54 |
| Br | 35 | 35 |
| Mg2+ | 12 | 12 -2 = 10 |
$$\therefore$$ N3-, F-, Na+
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