Which of the following reagents can be used to oxidise primary alcohols to aldehydes?

I. CrO₃ in anhydrous medium.

II. KMnO₄ in an acidic medium. 

III. Pyridinium chlorochromate.

IV. Heat in the presence of Cu at 573K. 

This is a multiple choice answer as classified in NCERT Exemplar

I. CrO₃ in anhydrous medium. 

II. Pyridinium chlorochromate. 

III.  Heat in the presence of Cu at 573K. 

KMnO₄ is a strong oxidising agent and oxidises the primary alcohol to ketone. Hence cannot be used as a reagent to oxidise primary alc