In the standardisation of Na2S2O3  using  K2Cr2O7 by iodometry, the equivalent weight of K2Cr2O7 is

In this reactionCr2O32−  is  changed  into  Cr+3  ion.So, equivalent weight of K2Cr2O7 =  molecular  wt.decrease  of  oxidation  number  ×  n(where n = No. of atoms of Cr)=molecular  wt.3 × 2=molecular  wt.6