The $pH$ of water is $7$. When a substance $Y$ is dissolved in water,the $pH$ becomes $13$. The substance $Y$ is a salt of......

$20\,mL$ of $0.1\,M\,NH_{4}OH$ is mixed with $40\,mL$ of $0.05\,M\,HCl$. The $pH$ of the mixture is nearest to. (Given: $K_{b}(NH_{4}OH) = 1 \times 10^{-5}, \log 2 = 0.30, \log 3 = 0.48, \log 5 = 0.69, \log 7 = 0.84, \log 11 = 1.04$) (in $.2$)

The aqueous solution of $CuSO_4$ is

Amongst the following,the total number of compounds whose aqueous solution turns red litmus paper blue is
$KCN$,$K_2SO_4$,$(NH_4)_2C_2O_4$,$NaCl$,$Zn(NO_3)_2$,$FeCl_3$,$K_2CO_3$,$NH_4NO_3$,$LiCN$

What is the $pH$ of a $K_2S$ solution?

If the $pKa$ of lactic acid is $5$,then the $pH$ of $0.005 \ M$ calcium lactate solution at $25^{\circ} \ C$ is $........ \times 10^{-1}$ (Nearest integer). The structure of lactic acid is given below: