Question

# The best reagent to convert $pent - 3 - en - 2 - ol$ into $pent - 3 - en - 2 - one$ is:A.Pyridinium chlorochromateB.Chromic anhydride in glacial acetic acidC.Acidic dichromateD.Acidic permanganate

As we all know, the conversion of $pent - 3 - en - 2 - ol$ into $pent - 3 - en - 2 - one$ is an oxidation reaction. The secondary alcohol is converted into ketone in this reaction.
So the best reagent used to convert $pent - 3 - en - 2 - ol$ into $pent - 3 - en - 2 - one$ is chromic anhydride in glacial acetic acid.
Note: There are a number of oxidizing agents which are used for the oxidation of alcohols but the most common reagents are chromic acid (${H_2}C{r_2}{O_7}$) and pyridinium chlorochromate or we can say $PCC$.