The bond angle and hybridization in ether $(CH_3OCH_3)$ is

What is $Y$ in the following reaction?
$C_2H_5I + NaOC_2H_5 \longrightarrow X + NaI$
$X + 2HI \xrightarrow{\Delta} 2Y + H_2O$

The products formed in the following reaction are $C_6H_5-OCH_3 + HI \xrightarrow{\text{heat}}$

What type of mechanism is followed by the dehydration of alcohol to form ether at $413 \text{ K}$?

Which of the following will be obtained by keeping ether in contact with air for a long time?

Which one of the following reactions will not lead to the desired ether formation in major proportion? (iso-$Bu$ $\Rightarrow$ isobutyl,sec-$Bu$ $\Rightarrow$ sec-butyl,$nPr$ $\Rightarrow$ $n$-propyl,${}^{t}Bu$ $\Rightarrow$ tert-butyl,$Et$ $\Rightarrow$ ethyl)