ANS:B - 0.1

The Schmidt number (𝑆𝑐Sc) is a dimensionless number used in fluid mechanics and heat transfer to quantify the relative importance of momentum diffusivity (viscosity) to mass diffusivity (diffusion). It is defined as the ratio of momentum diffusivity (𝐷𝑚Dm​) to mass diffusivity (𝐷D): 𝑆𝑐=𝐷𝑚𝐷Sc=DDm​​ For air at 750 K and 1 atm pressure, we can use approximate values for the viscosity and diffusivity of air. At this temperature and pressure, air behaves as an ideal gas, and the mass diffusivity of air (𝐷D) can be approximated using the Fuller equation. The Fuller equation gives the diffusivity of a gas as a function of its temperature and pressure. The Schmidt number for air can be estimated to be around 0.7 to 0.8 at standard conditions. However, at higher temperatures, it may slightly vary. Given the options provided, the closest approximation for the Schmidt number for air at 750 K and 1 atm pressure would be: 1