Which buffer solution out of the following will have $pH > 7$?

The $pH$ of blood does not appreciably change by a small addition of acid or a base because blood

How to prepare a buffer solution using ammonia $(pK_b = 4.75)$? What is the $pH$ of this buffer if the concentrations of ammonia and ammonium chloride are equal?

The $pOH$ of a basic buffer (e.g.,$NH_4OH/NH_4Cl$) is $5$. If the concentration of the salt is tripled while the concentration of the base remains constant,find the new $pOH$ value. (Given: $\log 3 = 0.48$)

What is the value of $pOH$ if a buffer solution is prepared by mixing equal volumes of $0.4 \ M$ $NH_4OH$ and $0.5 \ M$ $NH_4Cl$ solutions? $(pK_b = 4.730)$

The main buffer present in our blood is.....