Which of the following,upon treatment with $tert-BuONa$ followed by addition of bromine water,fails to decolourize the colour of bromine?

In the above reaction,product $B$ is:

$A$ compound $X$ on heating with alcoholic $AgNO_3$ gives a white precipitate. Oxidation of $X$ gives an acid with the formula $C_8H_6O_4$,which easily forms a cyclic anhydride on heating. The compound $X$ is

$CH_3CH(Br)CH_2CH_3 + \text{alc. } KOH \to$ ?

The reactivity order of the following molecules towards $S_N1$ reaction is:
$(I)$ Allyl chloride
$(II)$ Chlorobenzene
$(III)$ Ethyl chloride

Which of the following statements is true in the case of alkyl halides?