The diffusion flux is defined as: a) mass, per unit surface area, per unit time b) surface area, per unit time c) time, per unit surface area. d) the product of time and surface area, per unit mass

The correct answer is option a.

Explanation:

Diffusion flux is defined as movement of mas of atoms diffusing through the unit area in per unit time.It measured in ().

J = diffusion flux

A = Unit area A through which atoms moves.

M = mass of atoms passes in t interval of time.

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.