What happens when solid $\text{Na}_2\text{CO}_3$ dissolved in water?

What happens when $\text{CuSO}_4$ is dissolved in water?
Identify correct statements from the following

Identify conjugate acid and conjugate base for $\mathrm{HCO}_3^{-}$ion respectively

Find the concentration of sodium acetate when added to 0.1 M solution of acetic acid to form a buffer solution of $\mathrm{pH}=5.5$ ?

( $\mathrm{pK}_{\mathrm{a}}$ of $\mathrm{CH}_3 \mathrm{COOH}=4.5$ )