Which is the weakest nucleophile in an aprotic solvent?

Identify the reaction mechanisms for steps $I$ and $II$ in the given transformation:
$CH(Me)(Et)Cl + OH^- \rightarrow CH(Me)(Et)OH$
(Refer to the provided image for stereochemical outcomes $A$ and $B$)

What is the product formed when $1$-chlorobutane is treated with alcoholic potash $(KOH)$?

Which of the following reactions is expected to take place by the $S_N2$ mechanism?

Chlorination of toluene in the presence of light and heat followed by treatment with aqueous $NaOH$ gives:

Identify '$X$' and '$Y$' in the following sequence of transformations: $CH_3-CH_2-CH_2Br$ $\xrightarrow{X} \text{Product}$ $\xrightarrow{Y} CH_3-CH(Br)-CH_3$.