The general formula $C_nH_{2n}O_2$ can represent which of the following open-chain compounds?

What is the number of $-COOH$ groups present in phthalic acid?

Which among the following compounds is an amide?

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

Vinegar and butter are the sources for which of the following carboxylic acids respectively?

The molecular formula of the second homologue in the homologous series of mono carboxylic acids is . . . . . . .