Account for the following :
Preparation of ethers by acid dehydration of secondary or tertiary alcohols is not a suitable method.

Explanation

Acid dehydration of `2^(@)and3^(@)` alcohols give alkenes rather than ethers. Due to steric hindrance the nucleophilic attack by the alcohol molecule on the protonated alcohols molecule does not occur. The protonated `2^(@)and3^(@)` alcohols lose water molecules to form stable `2^(@)and3^(@)` carbocations.