Which of the following mixtures in water acts as a buffer?

One litre of an aqueous solution contains $0.15 \ mol$ of $CH_3COOH$ $(pK_a = 4.8)$ and $0.15 \ mol$ of $CH_3COONa$. After the addition of $0.05 \ mol$ of solid $NaOH$ to this solution,the $pH$ will be:

What is the ratio of concentration of salt to concentration of weak acid in a buffer solution to maintain its $pH$ value at $7.2$ $(pK_{a} = 6.2)$?

The $pH$ of blood in the human body is maintained by $CO_2$ and $H_2CO_3$. What is this process called?

To obtain a buffer which should be suitable for maintaining a $pH$ of about $4 - 5$,we need to have in solution,a mixture of

What is the $pH$ of a buffer solution prepared by mixing $0.01 \ M$ weak acid and $0.02 \ M$ salt of weak acid with a strong base? $(pK_{a} = 4.680)$