If the $pH$ of a mixture of $10 \, mL$ of $0.1 \, M \, NH_4OH$ and $10 \, mL$ of $1 \, M \, NH_4Cl$ solution is $8$,the $pK_b$ value of $NH_4OH$ is then closest to

Which of the following is a buffer solution?

What is the $pH$ of a buffer solution formed by mixing $0.01 \ M$ acetic acid and $0.05 \ M$ sodium acetate $(pK_a = 4.7447)$?

What is the ratio of $pH$ for a solution containing $1 \ mol$ $CH_3COONa$ + $0.5 \ mol$ $HCl$ per liter and another solution containing $1 \ mol$ $CH_3COONa$ + $1 \ mol$ $CH_3COOH$ per liter?

Buffer system helps to maintain blood $pH$ between .......

The $pH$ of an aqueous solution containing $1 \ M$ benzoic acid $(pK_{a}=4.20)$ and $1 \ M$ sodium benzoate is $4.5$. The volume of benzoic acid solution in $300 \ mL$ of this buffer solution is . . . . . . $mL$.