What is the number of possible enantiomeric pairs formed during the monochlorination of isopentane?

Which among the following alkyl halides gives more than one product upon dehydrohalogenation?

What is the bond length between carbon and bromine in $CH_3Br$ molecule (in $pm$)?

$A$ solution of $(+)-1$-chloro-$1$-phenylethane in toluene racemizes slowly in the presence of a small amount of $SbCl_5$ due to the formation of which of the following?

Consider the following reaction,
$C_2H_5Cl + AgCN \xrightarrow{EtOH / H_2O} \underline{X} \text{ (major)}$
Which one of the following statements is true for $\underline{X}$?
$(I)$ It gives propionic acid on hydrolysis
$(II)$ It has an ester functional group
$(III)$ It has a nitrogen linked to ethyl carbon
$(IV)$ It has a cyanide group

$50\%$ of the reagent is used for dehydrohalogenation of $6.45 \ g$ $CH_3CH_2Cl$. What will be the weight of the main product obtained (in $g$)? [At. mass of $H$,$C$,and $Cl$ are $1$,$12$,and $35.5 \ g \ mol^{-1}$ respectively]