F=HS2
G=HCO3
You seem to have difficulties with charge. Do the following it may clear the concepts a bit.
OK what is the equation of addition of H
+ toS
2-?
S
2- + H
+ HS
?? -
Fill in the charge so that net charge on LHS is equal to that on the RHS
Similarly for the other one..
CO
32- + H
+ HCO
3??Please write such equations for all others which you've got correct so that you may not confuse on some other question
And all the best for your exam. Prepare well