The orange colour of \( \mathrm{K_2Cr_2O_7} \) and purple colour of \( \mathrm{KMnO_4} \) is due to:
\( d \rightarrow d \) transitions in \( \mathrm{KMnO_4} \) and charge transfer transitions in \( \mathrm{K_2Cr_2O_7} \).
\( d \rightarrow d \) transitions in \( \mathrm{K_2Cr_2O_7} \) and charge transfer transitions in \( \mathrm{KMnO_4} \).
Charge transfer transition in both.
\( d \rightarrow d \) transitions in both.