$L$ $\xrightarrow[(ii) H_3O^{\oplus}]{(i) PhMgBr} M$ $\xrightarrow{CrO_3 / H^{\oplus}} N$ $\xrightarrow{Ph_3P=CH_2} Ph_2C=CH_2$
$L$ in the above sequence of reaction is/are (where $L \neq M \neq N$)

Enumerate different methods to prepare aldehyde compounds.

$Pentan-3-one$ is not obtained from:

Identify the name of the reaction: $C_6H_5CH_3 + CrO_2Cl_2 \xrightarrow{CS_2} C_6H_5CH(OCrOHCl_2)_2 \xrightarrow{H_3O^+} C_6H_5CHO$.

Identify the reagent used for the preparation of benzophenone from benzonitrile.

Give names of the reagents to bring about the following transformations:
$(i)$ $\text{Hexan-}1\text{-ol}$ to $\text{hexanal}$
$(ii)$ $\text{Cyclohexanol}$ to $\text{cyclohexanone}$
$(iii)$ $p\text{-Fluorotoluene}$ to $p\text{-fluorobenzaldehyde}$
$(iv)$ $\text{Ethanenitrile}$ to $\text{ethanal}$
$(v)$ $\text{Allyl alcohol}$ to $\text{propenal}$
$(vi)$ $\text{But-}2\text{-ene}$ to $\text{ethanal}$