In which case is the formation of $butanenitrile$ possible?

The order of $S_{N^1}$ reactivity in aqueous acetic acid solution for the compounds:
$(1)$ $CH_3-CO-CH_2-Cl$
$(2)$ $CH_3-CH_2-CH_2-Cl$
$(3)$ $(CH_3)_3C-Cl$

Match the $LIST$-$I$ with $LIST$-$II$:

List-$I$ (Reaction)	List-$II$ (Mechanism)
$A$. Williamson Synthesis	$I$. Electrophilic addition
$B$. Friedel-Crafts Reaction	$II$. Free radical substitution
$C$. Bromination of vinyl benzene	$III$. Nucleophilic substitution
$D$. Chlorination of toluene in light	$IV$. Electrophilic substitution

Choose the correct answer from the options given below:

Match the following:

Reactants	Products
$A$. $C_2H_5Cl$,moist $Ag_2O$	$I$. $CH_3CH_2ONO$
$B$. $C_2H_5Cl$,aqueous ethanolic $AgCN$	$II$. $C_2H_4$
$C$. $C_2H_5Cl$,aqueous ethanolic $AgNO_2$	$III$. $CH_3CH_2OH$
$D$. $C_2H_5Cl$,ethanolic $KOH$	$IV$. $CH_3CH_2NC$

The correct match is:

When $3-$methylbutan$-2-$ol is treated with $HBr$,the following reaction takes place:
$CH_3-CH(CH_3)-CH(OH)-CH_3 \xrightarrow{HBr} CH_3-C(Br)(CH_3)-CH_2-CH_3$
Give a mechanism for this reaction.
(Hint : The secondary carbocation formed in step $II$ rearranges to a more stable tertiary carbocation by a hydride ion shift from $3^{rd}$ carbon atom.)

When chloroform is treated with excess oxygen,it forms: