The major product of the following reaction is

Write the reaction steps for the following conversions:
$1.$ Propene to Propanal
$2.$ Ethanol to tert-Butyl ethyl ether

Why is the $C-O-H$ bond angle in alcohol slightly less than the tetrahedral angle,whereas the $C-O-C$ bond angle in ether is slightly greater?

Two isomeric compounds $I$ and $II$ are heated with $HBr$. The products obtained are

Ethers are prepared from alcohols by Williamson synthesis. Heating ethanol with sulfuric acid at $413 \ K$ gives ethoxyethane. Match the ether compounds in Column-$I$ with the products formed upon heating with $HI$ in Column-$II$.

Column-$I$ (Ether)	Column-$II$ (Product)
$(A)$ $CH_3CH_2-CH(CH_3)-CH_2-OCH_2CH_3$	$(i)$ $CH_3OH + CH_3-C(CH_3)_2-I$
$(B)$ $CH_3CH_2CH_2-O-C(CH_3)_2CH_2CH_3$	(ii) $C_6H_5OH + C_6H_5CH_2I$
$(C)$ $C_6H_5CH_2-O-C_6H_5$	(iii) $CH_3CH_2CH_2OH + CH_3CH_2-C(CH_3)_2-I$
$(D)$ $CH_3-C(CH_3)_2-O-CH_3$	(iv) $CH_3CH_2-CH(CH_3)-CH_2OH + CH_3CH_2I$

Which of the following is not a product of the reaction shown below?
$Ph-O-C_6H_{11} + PCl_5 \rightarrow \text{Products}$