$A$ 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

Which compound in each of the following pairs will react faster in $S_N2$ reaction with $OH^{-}$?
$(i)$ $CH_3-Br$ or $CH_3-I$
$(ii)$ $CH_3-C(CH_3)_2-Cl$ or $CH_3-Cl$

Classify the following reactions into one of the reaction types studied in this unit:
$(a)$ $CH_3CH_2Br + HS^{-} \rightarrow CH_3CH_2SH + Br^{-}$
$(b)$ $(CH_3)_2C=CH_2 + HCl \rightarrow (CH_3)_2ClC-CH_3$
$(c)$ $CH_3CH_2Br + HO^{-} \rightarrow CH_2=CH_2 + H_2O + Br^{-}$
$(d)$ $(CH_3)_3C-CH_2OH + HBr \rightarrow (CH_3)_2CBr-CH_2CH_3 + H_2O$

The increasing order of the boiling points of the major products $A$,$B$ and $C$ of the following reactions will be:

The product $B$ formed in the following reaction sequence is:

$Ph-CH(Br)-CH_2-CH_2-Br \xrightarrow[\Delta]{Zn-Cu} \text{Product}$. The product of the above reaction is: