[Hemidol]

Draw the resonance forms that fit the octet rule for sulfur trioxide, SO3.
(a) How many sigma bonds are there? How many pi bonds?
(b) What is the sulfur-oxygen bond order?
(c) Arrange the following species in order of decreasing S-O bond strength (strongest first, weakest last).
1. SO
2. SO32–
3. SO3
4. SO2


Here's my work...

For (a) 3 sigma bonds, 1 pi bond.
(b) 4/3 = 1.33

Unsure of how to answer (c).

[FeLiXe]

the first two sound good

for the last question I would arrange the species according to bond order. and if two molecules have the same bond order than the one with fewer oxygens should be stronger (because the elctron cloud can adjust better and you only need a lower degree of hybridization)