Regular use of which of the following fertilizers increases the acidity of the soil?

For the reaction $HCOO^{-} + H_2O \rightleftharpoons HCOOH + OH^{-}$,which of the following relations is correct?

Which of the following $0.1 \ M$ aqueous solutions will be basic?

$pH$ of a salt solution of weak acid $(pK_a = 4)$ and weak base $(pK_b = 5)$ at $25^{\circ}C$ is:

The $pH$ of an aqueous solution of alum is ....

The dissociation constants of $CH_3COOH$ and $HCN$ are $1.8 \times 10^{-5}$ and $7.2 \times 10^{-10}$ respectively. What is the relationship between the degree of hydrolysis of $KCN$ $(x_1)$ and $CH_3COOK$ $(x_2)$?