Which of the following Grignard reagents can be prepared?

The major product of the above reaction is:

Which reagent is used to convert an $Alkyl \ halide$ $(R-X)$ into an $Alkyl \ nitrite$ $(R-O-N=O)$?

When chloroform is treated with excess oxygen,it forms .....

An incorrect statement with respect to $S_N1$ and $S_N2$ mechanisms for alkyl halide is

Match the following reactions with their mechanisms:
$(A)$ $CH_3CH_2CH_2I \xrightarrow{aq. KOH}$
$(B)$ $(CH_3)_3CCl \xrightarrow{H_2O}$
$(I)$ $S_N1$
$(II)$ $E_2$
$(III)$ $S_N2$
$(IV)$ $E_1$