Which of the following anions has a valency of –3 ?

Which of the following anions has a valency of –3 ?

Nitride
Nitrate
Sulphide
Sulphate
This question was previously asked in
UPSC NDA-2 – 2024
The correct answer is A) Nitride.
Valency, in the context of ions, refers to the magnitude of the charge on the ion. An anion is a negatively charged ion.
– Nitride is the anion formed from a nitrogen atom gaining electrons to achieve a stable electron configuration. Nitrogen is in Group 15 and typically gains 3 electrons to form N³⁻. Thus, the valency of the nitride ion is -3.
– Nitrate is the polyatomic anion NO₃⁻, with an overall charge of -1.
– Sulphide is the anion formed from a sulphur atom gaining electrons. Sulphur is in Group 16 and typically gains 2 electrons to form S²⁻. The valency of the sulphide ion is -2.
– Sulphate is the polyatomic anion SO₄²⁻, with an overall charge of -2.
The charge on the ion directly corresponds to its valency (with the sign indicating whether it’s a cation or anion). Therefore, the anion with a valency of -3 is Nitride (N³⁻).