The iodometry titration of K2Cr2O7, Chromium is being reduced by Na2S2O3 from Cr6+ in K2Cr2O7, to Cr3+, according to the following reaction :
Cr2O7 2- + 6 e- → 2 Cr3+
Now, since in this redox titration reduction of Chromium involves a 6 electron change, therefore the equivalent weight of K2Cr2O7 = Molecular weight / 6.
Thus, the correct option is (2).
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