The structure of PCC is

• A

  $\mathrm{C}_6 \mathrm{H}_5 \stackrel{\oplus}{\mathrm{N}} \mathrm{HCrO}_2 \mathrm{Cl}^{\ominus}$
• B

  $\mathrm{C}_6 \mathrm{H}_5 \stackrel{\oplus}{\mathrm{N}} \mathrm{HCrO}_3 \mathrm{Cl}^{\ominus}$
• C

  $\mathrm{C}_5 \mathrm{H}_5 \stackrel{\oplus}{\mathrm{N}} \mathrm{HCrO}_2 \mathrm{Cl}^{\ominus}$
• Correct answer
  D

  $\mathrm{C}_5 \mathrm{H}_5 \stackrel{\oplus}{\mathrm{N}} \mathrm{HCrO}_3 \mathrm{Cl}^{\ominus}$

Solution

Pyridinium chlorochromate (PCC) can be prepared by the dissolution of chromium trioxide in aqueous $\mathrm{HCl}$. Addition of pyridine gives pridinium chlorochromate as orange cryotol.
PCC offers the advantage of the selective oxidation of alcohols to aldehydes, whereas many other reagents are less selective.

Hence, the correct answer is option: 'D'.