Ether and alcohol are $\ldots \ldots$ isomers.

Name the compound that is not an isomer of diethyl ether.

The two structures written below represent:

How are the following compounds related?

Identify the pairs of compounds that represent chain isomerism among the following:
$I. CH_3-CH_2-CH_2-CH_2-OH$ (Butan$-1-$ol)
$II. CH_3-CH_2-CH(OH)-CH_3$ (Butan$-2-$ol)
$III. (CH_3)_3C-OH$ ($2$-Methylpropan$-2-$ol)
$IV. (CH_3)_2CH-CH_2-OH$ ($2$-Methylpropan$-1-$ol)

Which statement is correct for compounds $A$ and $B$?