Give condensed and bond line structural formulas and identify the functional group$(s)$ present,if any,for:
$(a)$ $2,2,4-$Trimethylpentane
$(b)$ $2-$Hydroxy$-1,2,3-$propanetricarboxylic acid
$(c)$ Hexanedial

(N/A) $2,2,4-$Trimethylpentane
Condensed formula: $(CH_{3})_{3}CCH_{2}CH(CH_{3})_{2}$
Functional group: None (alkane)
$(b)$ $2-$Hydroxy$-1,2,3-$propanetricarboxylic acid
Condensed formula: $(HOOC)CH_{2}C(OH)(COOH)CH_{2}(COOH)$
Functional groups: Carboxylic acid $(-COOH)$ and alcoholic $(-OH)$ groups.
$(c)$ Hexanedial
Condensed formula: $OHC(CH_{2})_{4}CHO$
Functional group: Aldehyde $(-CHO)$ group.