hydrolysis of ester

i.
If concentrated sulphuric acid solution is used, hydrolysis of the ester occurs.
ester + H2O ≒ alkanoic acid + alkanol
(sulphuric acid is used as the catalyst.)

If pure or 98% sulphuric acid is used, no reaction occurs.
This is because of the absence of water.

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ii.
Theoretically, there is reaction because hydrolysis of the ester gives alkanoic acid which would react with the carbonate solution.

However, the reaction is extremely slow in the absence of acid catalyst. Actually, no reaction is observed even the reaction mixture is allowed to stand for a few days.

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iii.
Theoretically, there is reaction because hydrolysis of the ester gives alkanoic acid which would react with the hydrogencarbonate solution.

However, the reaction is extremely slow in the absence of acid catalyst. Actually, no reaction is observed even the reaction mixture is allowed to stand for a few days.

1 for sure, because the rate determinaing step is when the O of the C=O is protanated, if lots of H+ is around, the O of the C=O has a lot of chances to be protonated.

2 not at all, CO32- has no source of H+ to protonate the O of the C=O and the C will not have a resonance and the reaction simply wont go.

3 im pretty sure no, , maybe a little bit, because HCO3- is even a weaker acid than H2CO3 and H2CO3 is really a weak source of proton. HCO3- would simply take up prodon from solution instead to donating another H+.