Which of the following absorbs oxygen rapidly?

The $pH$ of $0.1 \ M$ solution of the following salts increases in the order:

What is the concentration of $[OH^-]$ in a mixture of $20 \ mL$ of $0.050 \ M \ HCl$ and $30 \ mL$ of $0.10 \ M \ Ba(OH)_2$ (in $M$)?

Two solutions $A$ and $B$,each of $100 \; L$,were made by dissolving $4 \; g$ of $NaOH$ and $9.8 \; g$ of $H_{2}SO_{4}$ in water,respectively. The $pH$ of the resultant solution obtained by mixing $40 \; L$ of solution $A$ and $10 \; L$ of solution $B$ is:

$CrO_4^{2-}$ (yellow) changes to $Cr_2O_7^{2-}$ (orange) in $pH = x$ and vice-versa in $pH = y$. Hence,$x$ and $y$ are

The hydrolysis constants of salts $M_1X$ and $M_2X$ formed from a strong acid and weak bases are $10^{-7}$ and $10^{-4}$ respectively. For base $M_3OH$,$K_b = 10^{-4}$. The decreasing order of basic strength is: