Which among the following reagents is used in the Rosenmund reduction?

Methyl ethyl ketone is prepared by the oxidation of

In the reaction $CH_3CN + 2H \underset{\text{Ether}}{}$ ${\xrightarrow{HCl}} X$ $\xrightarrow{\text{Boiling } H_2O} Y$; the product $Y$ is

Consider the following statements. Acetophenone can be prepared by:
$1$. Oxidation of $1$-phenylethanol
$2$. Reaction of benzaldehyde with methyl magnesium bromide
$3$. Friedel-Crafts reaction of benzene with acetyl chloride
$4$. Distillation of calcium benzoate

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 $\text{ethanal}$

In the reaction $RMgBr + HC(OEt)_3 \xrightarrow{Ether, H_3O^{+}} P$, the product $P$ is