The smallest wavelength possible for a sound wave in air is on the order of the separation

Question:

The smallest wavelength possible for a sound wave in air is on the order of the separation distance between air molecules. Find the order of magnitude of the highest-frequency sound wave possible in air, assuming a wave speed of 343 m/s, density 1.20 kg/m3, and an average molecular mass of 4.82 X 10─26 kg.