Which of the following is $NOT$ a dicarboxylic acid?

Name the following compounds according to the $IUPAC$ system of nomenclature:
$(i)$ $CH_3-CH(CH_3)-CH_2-CH_2-CHO$
$(ii)$ $CH_3-CH_2-CO-CH(C_2H_5)-CH_2-CH_2-Cl$
$(iii)$ $CH_3-CH=CH-CHO$
$(iv)$ $CH_3-CO-CH_2-CO-CH_3$
$(v)$ $CH_3-CH(CH_3)-CH_2-C(CH_3)_2-CO-CH_3$
$(vi)$ $(CH_3)_3C-CH_2-COOH$
$(vii)$ $OHC-C_6H_4-CHO-p$

What is the common name of $CH_3-CH=CH-COOH$?

What is a carbonyl group? Provide the different homologous series of carbonyl compounds.

Which among the following is a pair of monocarboxylic acids?

Which of the following is $NOT$ a dicarboxylic acid?