The structure of the product formed in the reaction given below is:

Assertion: $tert$-Butyl methyl ether is not prepared by the reaction of $tert$-butyl bromide with sodium methoxide.
Reason: Sodium methoxide is a strong nucleophile.

Which of the following ethers cannot be produced by Williamson ether synthesis?

Explain the following with an example.
$(i)$ Kolbe's reaction.
$(ii)$ Reimer-Tiemann reaction.
$(iii)$ Williamson ether synthesis.
$(iv)$ Unsymmetrical ether.

$A$ new carbon-carbon bond formation is possible in

$A$ $\xleftarrow{CH_3OH, CH_3O^{-}}$ ($1$-methyl$-6-$oxabicyclo[$3.1$.$0$]hexane) $\xrightarrow{CH_3OH, H_2SO_4}$ $B$
$A$ $\&$ $B$ are :