What type of ligand is the oxalate ion?

What is pH of a centimolar solution of $\mathrm{H}_2 \mathrm{SO}_4$ ?

What is the time needed to reduce the initial concentration of reactant to $10 \%$ in a first order reaction if its half life time is 10 minutes?

Which from following proteins acts as an enzyme to break protein to $\alpha$-amino acid?