Distinction between pairs of compounds
Propanol `(CH_(3)CH_(2)CH_(2)OH)` and Propanone `(CH_(3)COCH_(3))`

Explanation

These can be distinguished by iodoform test. Propanone, `CH_(3)COCH_(3)` contains the grouping-`COCH_(3)` linked to carbon and hence when warmed with `I_(2)//NaOH` (NaOI), it gives yellow ppt. of iodoform. In contrast, propanol does not contain the grouping `CH_(3)CHOH-` (attached to either H or C) and hence does not respond to iodoform test.
`underset("Propanone")(CH_(3)COCH_(3))+3NaOIoverset(NaOH//I_(2))rarrundersetunderset("(Yellow ppt.)")("Iodoform")(CHI_(3))darr+underset("Sod. acetate")(CH_(3)COONa)+2NaOH`