A(n) refers to two or more atoms held together by covalent bonds.
- community
- ion
- shell
- molecule
- isotope

Option (d) is the correct answer.

Explanation:

A covalent bond is defined as the bond formed by sharing of electrons between the two chemically combining atoms.

For example, atomic number of chlorine is 17 and it has 7 valence electrons.

To attain stability it need to gain one more electron.

So, when one chlorine atom chemically combines with another chlorine atom then there occurs sharing of electrons between the two. As a result, there will be sharing of electrons.

A molecule is defined as the specie that contains same type of atoms which are chemically combined together in a fixed ratio by mass.

the electronic configuration of an atom with eight electrons is 1s²2s²2p⁴. the orbital diagrams are shown in the figure.

as per the hunds rule:

1. electrons tend to avoid being in the same orbital as per as practicable.

2. electrons in different orbitals of the same energy will have their spin parallel.

this can be illustrated from the multiplicity of the orbitals of the atom. as there are four electrons in the p orbital and p orbital has 3 sub-shells. the electrons can be fed in different ways as shown in the figure but the correct orbital diagram will be as per the hunds rule.