Answer
$(a)$ $pI$ $>$ $pK_{a}$ of the $a$-carboxyl group and $pI$
Work Step by Step
$(a)$ both groups are ionized.
$(b)$ The pI of alanine is 6.01. From the Henderson Hasselbalch equation, 1/4,680 carboxyl groups and 1/4,680 amino groups are uncharged. The fraction of alanine molecules with both groups uncharged is the product of these fractions.
