Consider the following $E_1/S_N1$ reaction. The missing product$(s)$ is(are):

The product $(X)$ is:

Consider the reaction sequence: Alkyl halide $\xrightarrow[\text{Ether}]{Mg}$ Grignard Reagent $\xrightarrow{H_2O}$ Propane. The alkyl halide can be:

The correct order of increasing reactivity of $C-X$ bond towards nucleophile in the following compounds is:
$I$: Chlorobenzene (or aryl halide)
$II$: $2,4$-Dinitrochlorobenzene
$III$: $(CH_3)_3C-X$ ($3^o$ alkyl halide)
$IV$: $(CH_3)_2CH-X$ ($2^o$ alkyl halide)

Consider the above sequence of reactions. $151 \ g$ of $2-$bromopentane is made to react. The yield of the major product $P$ is $80 \%$ whereas the yield of $Q$ is $100 \%$. The mass of product $Q$ obtained is $........ \ g$. (Given molar mass in $g \ mol^{-1}$: $H: 1, C: 12, Br: 80$)

Give the chemical reactions for the following conversions:
$(1)$ $m$-nitrobenzoic acid from toluene
$(2)$ $m$-chloronitrobenzene from benzene
$(3)$ $n$-propyl bromide from $1, 2$-dibromopropane