Explanation

(b)
Fats are esters of higher fatty acids with glycerol, hence on alkaline hydrolysis, they give back glycerol and sodium or potassium salt of acid (this is called soap).
$CH_{2}OCOR\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ CH_{2}OH\ \$
$|\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ |\ \$
$CHOCOR + 3NaOH\ \rightarrow CHOH + 3RCOONa\ \$
$|\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ |$
${CH}_{2}OCOR\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ {CH}_{2}OH$
fat