Answer:
Shared (bonding) electrons : 8
Unshared (lone, non-bonding) electrons : 16
Explanation:
The Lewis dot stricture of the molecule attached to this answer shows us all the valence electrons present in the molecule.
Altogether, we have a total number of 24 valence electrons in SO3.
There are eight electrons shared between atoms of elements, these are the bonding electrons.
There are sixteen electrons that are not shared between atoms of elements, These are the lone or non-bonding electrons.
Hence, there are four shared pairs of electrons and eight pairs of unshared electrons.