question_answer

The correct sequence of decreasing number of \[\pi \]-bonds in the structure of \[{{H}_{2}}S{{O}_{3}},\,{{H}_{2}}S{{O}_{4}}\] and \[{{H}_{2}}{{S}_{2}}{{O}_{7}}\] is:           [JEE Online 09-04-2017]

A)  \[{{H}_{2}}{{S}_{2}}{{O}_{7}}>{{H}_{2}}S{{O}_{3}}>{{H}_{2}}S{{O}_{4}}\]

B)  \[{{H}_{2}}{{S}_{2}}{{O}_{7}}>{{H}_{2}}S{{O}_{4}}>{{H}_{2}}S{{O}_{3}}\]

C)  \[{{H}_{2}}S{{O}_{4}}>{{H}_{2}}{{S}_{2}}{{O}_{7}}>{{H}_{2}}S{{O}_{3}}\]

D)  \[{{H}_{2}}S{{O}_{3}}>{{H}_{2}}S{{O}_{4}}>{{H}_{2}}{{S}_{2}}{{O}_{7}}\]

Correct Answer: B

Solution :

                \[{{H}_{2}}{{S}_{2}}{{O}_{7}}=HO-\underset{\begin{smallmatrix}  \,|| \\  O \end{smallmatrix}}{\mathop{\overset{\begin{smallmatrix}  O \\  \,|| \end{smallmatrix}}{\mathop{S}}\,}}\,-O-\underset{\begin{smallmatrix}  \,|| \\  O \end{smallmatrix}}{\mathop{\overset{\begin{smallmatrix}  O \\  \,|| \end{smallmatrix}}{\mathop{S}}\,}}\,-OH\]                 \[{{H}_{2}}S{{O}_{4}}=HO-\underset{\begin{smallmatrix}  \,|| \\  O \end{smallmatrix}}{\mathop{\overset{\begin{smallmatrix}  O \\  \,|| \end{smallmatrix}}{\mathop{S}}\,}}\,-OH\]