n -pentane and isopentane can be distinguished by

Step-by-step solution

KMnO ₄ oxidises 3^ H of isopentane to 3^ - OH group. As a result, pink violet colour of KMnO ₄ get discharged. In constants, 1^ or 2^ H of n -pentane does not get oxidised to the corresponding OH group and hence colour of KMnO ₄ is not discharged.