$$\begin{aligned} & \mathrm{CH}_3-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_2 \mathrm{OH} \stackrel{\mathrm{PCC}}{\longrightarrow} \\\\ & \mathrm{CH}_3-\mathrm{CH}=\mathrm{CH}-\mathrm{CHO} \end{aligned}$$

Hybridisation change involved at $$\mathrm{C}$$-$$1$$ in the above reaction.

A better reagent to oxidise primary alcohols into aldehyde is

Y in the above reaction is

An organic compound with molecular formula $$\mathrm{C}_7 \mathrm{H}_8 \mathrm{O}$$ dissolves in $$\mathrm{NaOH}$$ and gives a characteristic colour with $$\mathrm{FeCl}_3$$. On treatment with bromine, it gives a tribromo derivative $$\mathrm{C}_7 \mathrm{H}_5 \mathrm{OBr}_3$$. The compound is