Which reactants are Lewis acids in these four reactions?

[Intr3pid]

Homework Statement

Which of the following reactants are lewis acids?

H3O+ + N2H4 --> N2H5+ + H2O
Ag+ + Cl- --> AgCl
CaO + SO2 --> CaSO3
GaCl3 + Cl- --> GaCl4

Homework Equations

Lewis acids are electron pair acceptors while lewis bases are electron pair donors

The Attempt at a Solution

My answer on which reactants are the lewis acids:

H3O+
Cl-
SO2
GaCl3

 

[chemisttree]

You almost got everything right. Try to reconcile the answer to the second and fourth reaction.