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)

The answer should be B - Nitrogen Dioxide.
The volume is 100mL.
The mass is 1.5kg which is equal to 1500g.
Thus, the density is 1500g / 100mL which is 15g/mL.
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