Explanation

(a)
In alkaline medium, alanine exists as anion.
$CH_{3} - CH - NH_{2}\ \underset{(pH > 7)}{\overset{\ \ \ \ \ Basic\ medium\ \ \ \ \ }{\rightarrow}}\ CH_{3} - CH - NH_{2}\ \$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ |\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ |\$
$\ \ \ \ \ \ \ \ \ \ \ \ \ COOH\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ {COO}^{-}$
Alanine