The order of reactivity $3^{\circ} \text{ halide} > 2^{\circ} \text{ halide} > 1^{\circ} \text{ halide} > CH_3X$ represents which of the following reactions?

The major product obtained in the following reaction is $C_2H_5ONa + (CH_3)_3C-Cl \rightarrow$

The rate of $S_{N}1$ reaction for the given compounds is:

Which one of the following is more readily hydrolysed by $S_{N}1$ mechanism?

When $tert$-butyl bromide is heated with silver fluoride,the major product obtained is

Consider the $S_N1$ solvolysis of the following halides in aqueous formic acid:
$(I)$ $CH_3-CH(CH_3)-CH(Br)-CH_3$
$(II)$ $CH_3-C(CH_3)(Br)-CH_3$
$(III)$ $C_6H_5-CH(Br)-C_6H_5$
$(IV)$ $C_6H_5-CH(Br)-CH_3$
Which one of the following is the correct sequence of the halides given above in the decreasing order of their reactivity?