Let’s look at the declension of third person neuter pronouns in the singular:

Nom : id

Gen : eius

Dat : eī

Acc : id

Abl : eō

Voc : –

Now the declension of third person pronouns in the plural:

Nom : ea

Gen : eōrum

Dat : eīs, iīs

Acc : ea

Abl : eīs, iīs

Voc : –