What is $Z$ in the following sequence of reaction?
$Z$ $\xrightarrow{PCl_5} X$ $\xrightarrow{Alc. KOH} Y$ $\xrightarrow{dil. H_2SO_4} Z$

What is the increasing order of reactivity of the following alkyl halides in the Williamson synthesis?
$I. \, CH_2 = CHCH_2Cl$
$II. \, CH_3CH_2CH_2Br$
$III. \, (CH_3)_3CCH_2Br$
$IV. \, CH_3CH_2CH_2Cl$

Match the reactions given in Column-$I$ with the bond broken in Column-$II$.

Column-$I$ (Reaction)	Column-$II$ (Bond broken)
$(A)$ $RCH_2OH \xrightarrow{CrO_3} RCHO$	$(i)$ $C-O$ bond breaks.
$(B)$ Phenol $\xrightarrow{HNO_3}$ $p$-Nitrophenol + $o$-Nitrophenol	(ii) $O-H$ bond breaks.
$(C)$ Phenol + $NaOH \rightarrow$ Sodium phenoxide + $H_2O$	(iii) $O-H$ and $C-H$ bonds break.
$(D)$ $CH_3CH_2CH_2OH \xrightarrow{H_2SO_4, \Delta} CH_3CH=CH_2$	(iv) $C-H$ bond breaks.

What can be concluded from the order of boiling points of ether,carbon tetrachloride,ethanol,and water?

Which of the following reactions produce $n$-butanol?

Match the chemical conversions in List-$I$ with the appropriate reagents in List-$II$ and select the correct answer using the code given below the lists:
List-$I$:
$P$. $tert$-butyl chloride $\rightarrow$ isobutylene
$Q$. Sodium $tert$-butoxide $\rightarrow$ $tert$-butyl ethyl ether
$R$. $1$-methylcyclopentene $\rightarrow$ $1$-methylcyclopentanol
$S$. $1$-methylcyclopentene $\rightarrow$ $2$-methylcyclopentanol (trans-isomer)
List-$II$:
$1$. $(i) \ Hg(OAc)_2; (ii) \ NaBH_4$
$2$. $NaOEt$
$3$. $EtBr$
$4$. $(i) \ BH_3; (ii) \ H_2O_2/NaOH$
Codes: $P \quad Q \quad R \quad S$