→ Can use an oxidation reaction to determine the unknown substance.

→ 2-methylpropan-1-ol is a primary alcohol whereas 2-methylpropan-2-ol is a tertiary alcohol.

→ Hence when undergoing oxidation with acidified potassium permanganate solution, the solution containing the primary alcohol will oxidise and experience a colour change from purple to colourless. The tertiary alcohol will not undergo oxidation.

\(\Rightarrow D\)