$KCN$ reacts readily to give a cyanide with:

How many of the four monochloro derivatives of $(CH_3)_2CHCH_2CH_3$ are optically active?

The order of relative reactivity of the given halides towards $S_N2$ reaction is :

Predict the order of reactivity of the following compounds in $S_N1$ reaction.
$(I)$ $C_6H_5-CH_2Br$
$(II)$ $C_6H_5-CH(C_6H_5)Br$
$(III)$ $C_6H_5-CH(CH_3)Br$
$(IV)$ $C_6H_5-C(CH_3)(C_6H_5)Br$

If all the nucleophilic substitution reactions at saturated carbon atoms in the above sequence of reactions follow $S_N2$ mechanism, then $\underline{E}$ and $\underline{E}$ will be respectively,

The major product obtained in the following reaction is: