Tiny crystals of purple $ ext{KMnO}_4$ ($M_r = 158$) and orange $ ext{K}_2 ext{Cr}_2 ext{O}_7$ ($M_r = 294$) were each placed at the centre of separate petri dishes that had been filled with agar jelly. They were then left in the same set of physical conditions. After a period of time, the colour of each substance had diffused outward as shown. The arrows show the relative distances moved by particles of each substance. Which of the following statements is correct?
- ADiffusion is faster in dish 1 because the mass of the particles is greater.
- BDiffusion is faster in dish 2 because the mass of the particles is greater.
- CDiffusion is slower in dish 1 because the mass of the particles is smaller.
- DDiffusion is slower in dish 2 because the mass of the particles is greater.