Concept:Valency is the combining capacity of an atom, determined by the number of electrons it can gain, lose, or share.
Explanation:Phosphorus has atomic number
15.
Its electronic configuration is
2,8,5.
It has
5 electrons in its valence shell.
It can gain
3 electrons to complete its octet, so its valency is
3.
It can also lose or share
5 electrons by exciting electrons to vacant
3d orbitals.
In the excited state, the configuration is
[Ne]3s13p33d1, giving
5 unpaired electrons.
Thus, phosphorus exhibits a valency of
3 as well as
5.
Answer:The valency of phosphorus is
3 and
5.
Therefore, the correct option is D.
3,5.
