Consider some oxy-acids of sulphur.How many of the given oxy-acids have (S – S) linkage (either single or double bond) in their structure?(A) H2S2O4(B) H2S4O6(C) H2S2O3(D) H2S2O7(E) H2S2O8(F) H2S2O6(G) H2S5O6

To answer this question, we need to understand the structure of these oxy-acids of sulphur.

(A) H2S2O4: This is known as dithionic acid. It has a (S-S) linkage. (B) H2S4O6: This is known as tetrathionic acid. It has two (S-S) linkages. (C) H2S2O3: This is known as dithionous acid. It does not have a (S-S) linkage. (D) H2S2O7: This is known as pyrosulphuric acid. It does not have a (S-S) linkage. (E) H2S2O8: This is known as peroxodisulphuric acid. It does not have a (S-S) linkage. (F) H2S2O6: This is known as dithionate. It has a (S-S) linkage. (G) H2S5O6: This is known as pentathionic acid. It has four (S-S) linkages.

So, the oxy-acids of sulphur that have (S – S) linkage in their structure are H2S2O4, H2S4O6, H2S2O6, and H2S5O6. Therefore, the answer is 4.