Hybridisation of oxygen in diethyl ether is

Methyl vinyl ether,$H_2C=CH-OCH_3$,reacts with $Br_2/CH_3OH$. If methanol is reacting as water would,and if this reaction follows a typical mechanism of electrophilic addition,what would be the expected product?

Heating tert-butyl methyl ether with $HI$ gives which of the following mixtures?

The major products formed in the reaction of $t$-butyl methyl ether with $HI$ are

Identify the product $(A)$ of the following reaction:
$C_2H_5-O-C_2H_5 + CO \xrightarrow[500 \text{ atm}]{BF_3 / 150^{\circ}C} A$

In the following reaction sequence,structures of $A$ and $B$,respectively will be