Protons, neutrons..................................
Answer:
a)1.404 E-10 m^2/s
b)1.438 E-12 m^2/s
Explanation:
Diffusion Coefficients can be calculated at different temperatures taking into account the energy of the diffusive process, remember that this process takes place in the interstices of the solid, and gets with higher temperatures due to the higher kinetic energy of the particles.

a) For α-iron (BCC)

b) For γ-iron (FCC)

In a solid, molecules are packed together, and it keeps its shape. Liquids take the shape of the container. Gases spread out to fill the container. Solid is one of the three main states of matter, along with liquid and gas.
Hope that helps!
A matter in the solid phase has a fixed shape and volume.