Which one of the following salts gives an acidic solution in water?

Find the equilibrium constant for the equilibrium reaction:
$HCOO^{-} + H_2O \rightleftharpoons HCOOH + OH^{-}$
Given that the dissociation constant of formic acid is $K_a(HCOOH) = 1.8 \times 10^{-4}$.

Which of the following is a basic salt?

Which among the following salts is formed from a strong base and a weak acid?

Find out $K_a$ for the acid when the degree of hydrolysis of $0.1 \ M \ CH_3COONa$ is $1 \ \%$.

$A$ few grams of sodium carbonate $(Na_2CO_3)$ is added to $1 \ L$ of water. What is the $pH$ or $pH$ range of the resultant solution?