Which of the following reactions can be used to convert an alkyl halide into an alcohol?

What is the order of reactivity for the $S_{N}2$ reaction among the following alkyl halides?

Which of the following reagents,when heated with ethyl chloride,forms ethylene?

Which one of the following is the best catalyst for the reaction shown below?
$CH_3(CH_2)_8CH_2Br \xrightarrow[benzene]{KCN} CH_3(CH_2)_8CH_2CN$

Which of the following pairs is/are correctly matched?

Reaction	Product
$I$. $RX + AgCN$	$RNC$
$II$. $RX + KCN$	$RCN$
$III$. $RX + KNO_2$	$RONO$
$IV$. $RX + AgNO_2$	$RNO_2$

Consider the reaction sequence shown below:
$Br-CH_2-CHO$ $\xrightarrow[\text{dry } HCl \text{ gas}]{\text{EtOH (excess)}} A$ $\xrightarrow{^tBuO^-K^+} B$
[Where $Et \Rightarrow -C_2H_5$,$^tBu \Rightarrow (CH_3)_3C^-$]
Identify the major products $A$ and $B$ formed respectively.