Question

Atomicity of phosphorus is:
(A) 1
(B) 2
(C) 4
(D) 6

Answer 1

Hint: The atomicity of an element is defined as the number of the atoms present in the molecule of the element. An example would be that the molecule of oxygen is composed of two atoms so its atomicity is equal to 2.

Complete step by step solution
The elements can have different atomicity depending on their bonding patterns. For example most of the metals are monoatomic such as sodium, potassium, calcium, etc. the non-metallic gases are generally diatomic such as hydrogen, oxygen, chlorine, etc. This is because the non-metals have the tendency to form covalent bonds to satisfy their octet configuration while metals have the tendency to donate electrons to satisfy their octet in general.
The noble gases are an exception, they are monoatomic in spite of being non-metal due to their stable octet configuration. Phosphorous is a non-metal whose atomicity is equal to four and hence these four atoms are bonded to each other by covalent bonding to form the $ {{\text{P}}_{\text{4}}} $ molecule.
Hence, the correct answer is option C.

Note
The examples of multi-atomic elements are very few. There is ozone which is triatomic, sulphur which is octaaomic and phosphorus which is tetraatomic. The metals and some other elements such as carbon do not have simple structure but consist of a very large and indefinite number of atoms bonded together. Their atomicity cannot be determined and hence considered to be 1. The atomicity also varies depending on the allotropes of the element.