I think D, not sure though!
Diffusion is a process that results from the random motion of molecules and results in a net movement of matter from a high-concentration region to a low-concentration zone.
Answer is: the nature of the initial nickel sulfide mixture is a suspension.
Suspension<span> is a </span>heterogeneous mixture (solute<span> particles do not </span>dissolve), <span>that contains </span>solid<span> particles (in this example nickel sulfide or NiS) sufficiently large for </span>sedimentation. <span> The internal phase (solid nickel sulfide) is dispersed throughout the external phase (water).</span>
Answer:
One way is through fossil fuels. When people burn fossil fuels it enters the atmosphere as carbon dioxide gas. Another way is through animals. Most animals exhale carbon dioxide as a waste product which gets into the atmosphere.
