Carbonyl compounds are usually

Which among the following is an aromatic aldehyde?

What is the structure of the third member of the homologous series of aliphatic aldehydes?

Write the structures of the following compounds:
$(i)$ $\alpha$-Methoxypropionaldehyde
$(ii)$ $3$-Hydroxybutanal
$(iii)$ $2$-Hydroxycyclopentanecarbaldehyde
$(iv)$ $4$-Oxopentanal
$(v)$ Di-sec-butyl ketone
$(vi)$ $4$-Fluoroacetophenone

Match the $IUPAC$ name of the carbonyl compound in Column-$I$ with its structure in Column-$II$ and its common name in Column-$III$.

Column-$I$ ($IUPAC$ name)	Column-$II$ (Structure)	Column-$III$ (Common name)
$A. 4$-oxopentanal	$i. CH_3CH_2CH_2CH_2CHO$	$p. \text{Acetyl acetone}$
$B. \text{Ethane-}1,2\text{-dial}$	$ii. CH_3COCH_2CH_2CHO$	$q. \text{Valeraldehyde}$
$C. \text{Pentane-}2,4\text{-dione}$	$iii. CHOCHO$	$r. \beta\text{-acetyl propionaldehyde}$
$D. \text{Pentanal}$	$iv. CH_3COCH_2COCH_3$	$s. \text{Glyoxal}$

Identify the aldehyde from the following in which the aldehydic group $(-CHO)$ is $NOT$ attached to any $sp^3$ hybridized carbon atom.