Distinction between pairs of compounds
Butan-1-ol `(CH_(3)CH_(2)CH_(2)CH_(2)OH)` and butan-2-ol `(CH_(3)CHOHCH_(2)overset(3)(CH_(3)))`

Explanation

Iodoform test helps to distinguish these. Butan-2-ol contains the grouping `CH_(3)CHOH-` So, this when warmed with `I_(2)//NaOH` or NaOI, yellow ppt. of iodoform `(CHI_(3))` are formed. Butan-1-ol which does not contain `CH_(3)Coverset(3)HOH-` grouping does not give this test.
`underset("Butan-2-ol")(CH_(3)CHOHCH_(2)CH_(3))+NaOIrarrunderset("Butan-2-one")(CH_(3)COCH_(2)CH_(3))+NaI+H_(2)O`
`CH_(3)COCH_(2)CH_(3)+3NaOIrarrCHI_(3)darr+underset("Sod. propanoate")(CH_(3)CH_(2)COONa)+2NaOH`