An isomer of $C_3H_6Cl_2$ gives acetone on heating with aqueous $KOH$. This isomer is .......

Which of the following is added to chloroform to slow down its aerial oxidation in the presence of light?

Which compound has the highest reactivity towards $S_{N}2$ reaction?

What are $X, Y$ and $Z$ in the following reactions?
$(CH_3)_3 C-O^- Na^+ + CH_3 CH_2 Br \longrightarrow X + NaBr$
$(CH_3)_3 C-Br + CH_3 CH_2 O^- Na^+ \longrightarrow Y + Z$

$C_2H_5Cl + KCN$ $\xrightarrow{} X$ $\xrightarrow{\text{Hydrolysis}} Y.$
$X$ and $Y$ are:

$A$ dihalogen derivative '$X$' of a hydrocarbon with three carbon atoms reacts with alcoholic $KOH$ to give another hydrocarbon which forms a red precipitate with ammoniacal $Cu_2Cl_2$. '$X$' gives an aldehyde upon reaction with aqueous $KOH$. What is the compound '$X$'?