$C_n{H}_{2n+2}O$ is the general formula of ethers. To exhibit the functional group isomerism 'n' must be minimum

(Hint)

        Alcohols containing one ‘C’ atom cannot exihibit functional isomerism with ethers because ethers contain minimum two ‘C’ atoms. Hence to exihibit functional isomerism, ‘n’ must be minimum two.