Which of the following halogenated compounds is not used in Williamson$'$s synthesis?

Write the names of reagents and equations for the preparation of the following ethers by $Williamson$ synthesis:
$(i)$ $1-Propoxypropane$
$(ii)$ $Ethoxybenzene$
$(iii)$ $2-Methoxy-2-methylpropane$
$(iv)$ $1-Methoxyethane$

Ethers can be prepared by Williamson synthesis in which an alkyl halide is reacted with sodium alkoxide. Di-tertiary ether cannot be prepared by this method. Explain.

Explain the preparation of ethers by dehydration of alcohols and its mechanism with a suitable example.

From Williamson's synthesis,the preparation of which of the following is possible?

Which among the following is the method for the preparation of ethers?