Question

How many resonance structures are there for so3?

Answer 1

When you draw the Lewis structure, you first get the three structures at the top.

In each of them, S has a formal charge of +2 and two of the O atoms have formal charges of -1.

In each of the three structures in the middle, S has a formal charge of +1 and one of the O atoms has a formal charge of -1.

In the bottom structure, all atoms have a formal charge of zero.

soooo
There are seven resonance structures for SO3