Diffusion Method and Separation of Gases

Diffusion is the process of intermixing of gases. Diffusion of gases occurs due to the random motion of gas molecules from a region of higher concentration to a region of lower concentration. The rate of diffusion of gases depends upon their molecular mass, temperature, and pressure. The diffusion method is used for the separation of gases based on their molecular mass, size, and solubility.

Pair of Gases that cannot be Separated by Diffusion Method

The correct answer is option 'D', i.e., CO2 and N2O. These two gases cannot be separated by the diffusion method because they have almost the same molecular mass and size. The rate of diffusion of gases is directly proportional to their molecular mass. When two gases have the same molecular mass, they diffuse at the same rate and cannot be separated by the diffusion method.

Explanation of Other Options

a) CO2 and NO2: These two gases can be separated by the diffusion method because they have different molecular masses and sizes.

b) CO2 and N2O2: These two gases can be separated by the diffusion method because they have different molecular masses and sizes.

c) CO2 and H2: These two gases can be separated by the diffusion method because they have different molecular masses and sizes.

Conclusion

In conclusion, the diffusion method is used for the separation of gases based on their molecular mass, size, and solubility. CO2 and N2O cannot be separated by the diffusion method because they have almost the same molecular mass and size.