Question

The difference in the number of $\sigma$ and $\pi$ bonds in trimer of $S{O}_{3}i.e{S}_3{O}_9$ (consider no coordinate bond to be present )

Answer 1

$\sigma =3+9=12$$,\pi bond=6$

Thus, The difference in the number of $\sigma$ and $\pi$ bonds in trimer of $S{O}_3$ is $12-6=6$