Doubt from chemical bonding

solved
chemical-bonding
lewis-structure
finding-formal-charge
easy
pp
#1

Which lewis structure is correct ?

#2

The one that has three double bonds with oxygen atoms is correct, you can see the structure exist in significant compounds like caros acid H2SO5.

#3

The structure of first image with 2 Double bond ( S = O ) are present is the correct lewis structure.

#4

Lewis structure of CO4 2- ion is

#5

I don't think there is any CO4 2-.
Because C can only have 4 bonds and, no combination is giving me CO4 2- ion