The hydrolysis of optically active $2-$bromobutane with aqueous $NaOH$ results in the formation of:

$A$ 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?

In the $S_{N}2$ substitution reaction $R-Br + Cl^- \xrightarrow{DMF} R-Cl + Br^-$,which of the following will have the highest rate?

$C_2H_5I$ $\xrightarrow{\text{alc. } KOH} X$ $\xrightarrow{Br_2} Y$ $\xrightarrow{KCN} Z$; $Z = \dots$

Explain why:
$(i)$ the dipole moment of chlorobenzene is lower than that of cyclohexyl chloride?
$(ii)$ alkyl halides,though polar,are immiscible with water?
$(iii)$ Grignard reagents should be prepared under anhydrous conditions?

Write a note on Grignard Reagent.