Question 7

Peroxide linkage refers to the $-O-O-$ bond.

(A) $H_2S_2O_7$ (Pyrosulfuric acid) has an $S-O-S$ bond ($HO-SO_2-O-SO_2-OH$).

(B) $H_2S_2O_8$ (Peroxodisulfuric acid or Marshall's acid) contains an $S-O-O-S$ linkage ($HO-SO_2-O-O-SO_2-OH$).

(C) $H_2S_2O_5$ (Pyrosulfurous acid) contains an $S-S$ bond ($HO-SO_2-SO-OH$).

(D) $H_2SO_5$ (Peroxomonosulfuric acid or Caro's acid) contains an $S-O-O-H$ linkage ($HO-O-SO_2-OH$).