Identify the correct sequence of increasing number of $\pi$-bonds in the structure of the following

Question

Identify the correct sequence of increasing number of $\pi$-bonds in the structure of the following molecules : 
(l) $\mathrm{H}_2 \mathrm{~S}_2 \mathrm{O}_6$ 
(II) $\mathrm{H}_2 \mathrm{~S}_2 \mathrm{O}_3$ 
(III) $\mathrm{H}_2 \mathrm{~S}_2 \mathrm{O}_5$

Professor PC Thomas Classes · Answer

See detailed solution for explanation.