Graham's law of diffusion states that the rate of diffusion of a gas is inversely proportional to the square root of its molar mass. To find the diffusion coefficient D of a gas, we can use the following equation:D = D * M / MWhere:D = diffusion coefficient of the reference gas air in this case M = molar mass of the reference gas air M = molar mass of the given gasFirst, we need to find the diffusion coefficient of air. For this, we can use the Chapman-Enskog equation:D = 3.0 10 * T/ / P * * Where:T = temperature in Kelvin 25C = 298.15 K P = pressure in atm assuming 1 atm = collision diameter for air, approximately 3.62 10 m = collision integral for air, approximately 1.0 Plugging in the values:D = 3.0 10 * 298.15 / / 1 * 3.62 10 * 1.0 D 2.0 10 m/sNow, we can find the diffusion coefficient of the given gas. The molar mass of air is approximately 29 g/mol. The molar mass of the given gas is 16 g/mol.D = 2.0 10 * 29 / 16D 2.0 10 * 29 / 4D 1.45 10 m/sSo, the diffusion coefficient of the gas with a molar mass of 16 g/mol in air at 25C is approximately 1.45 10 m/s, assuming the gas follows Graham's law.