The most important buffer in the blood consists of

Which of the following does not form a buffer solution?

How many moles of sodium acetate should be added to $1 \ L$ of a $0.1 \ M$ solution of $CH_3COOH$ to give a solution of $pH = 5.5$? (Given: $pK_a$ of $CH_3COOH = 4.5$)

$A$ buffer solution is prepared by mixing $0.2 \ M \ NH_4OH$ and $1 \ M \ NH_4Cl$. What is the $pH$ value of the buffer solution? (Given $pK_b = 4.744$)

Find the value of $\frac{[NaCN]}{[HCN]}$ given the $pH$ of the buffer solution of $NaCN$ and $HCN$ is $9.3$ and $K_a$ of $HCN$ is $5 \times 10^{-10}$.

What are buffer solutions? Explain types of buffer solutions with examples.