Consider the following list of reagents: Acidified K2Cr2O7, alkaline KMnO4, CuSO4, H2O2, Cl2, O3, FeCl3 and Na2S2O3. The total number of reagents that can oxidise aqueous iodide to iodine is:

K2Cr2O7 + 7H2SO4 + 6KI → 4K2SO4 + Cr2(SO4)3 + 3I2 + 7H2O
2CuSO4 + 4KI → Cu2I2 + I2 + 2K2SO4
H2O2 + 2KI → I2 + 2KOH
Cl2 + 2KI → 2KCl + I2
O3 + 2KI + H2O → 2KOH + I2 + O2
2FeCl3 + 2KI → 2FeCl2 + I2 + 2KCl
2KMnO4 + KI + H2O → KIO3 + 2MnO2 + 2KOH

Acidified K2Cr2O7, CuSO4, H2O2, Cl2, O3, and FeCl3 can oxidize iodide ions to iodine. Alkaline KMnO4 also oxidizes iodide to iodate (IO3-), which is a higher oxidation state than iodine (I2). However, the question asks about the oxidation to iodine (I2), so only the reagents listed above are suitable. Na2S2O3 (sodium thiosulfate) is a reducing agent, not an oxidizing agent, and therefore cannot oxidize iodide to iodine. Therefore, a total of 6 reagents can oxidize aqueous iodide to iodine.