What is the mole ratio of CrO42- to S2O32- in an acidic medium, given mean titre readings?

Step 1: Determine the mean titre volume.
The accurate titre readings are $21.4 \text{ cm}^3$ and $21.4 \text{ cm}^3$.

$$\text{Mean titre} = \frac{21.4 \text{ cm}^3 + 21.4 \text{ cm}^3}{2} = 21.4 \text{ cm}^3$$

1. Establish a mole relationship between the $\text{CrO}_4^{2-}$ and $\text{S}_2\text{O}_3^{2-}$ in acidic medium.
The relevant chemical equations are:

1. Oxidation of iodide by chromate: $$$$