It’s important because it provides so other scientists can repeat the experiment to prove if that theory is true or not.
For apex the answer is no solution
Answer : The value of diffusion coefficient is, 
Explanation :
Formula used :

where,
D = diffusion coefficient = ?
= 
= 
R = gas constant = 8.314 J/mol.K
T = temperature = 
Now put all the given values in the above formula, we get:


Thus, the value of diffusion coefficient is, 
An atom cannot be broken down any smaller whereas a compound is made up of atoms and can be broken down into smaller pieces (the individual atoms that make it up)
Hope this helps!