8. What makes pure substance different from mixture? A) Pure substance has different properties while mixture has constant properties. B) Pure substance has combination of substances while mixture has no combination C) Pure substance contains two or more molecules while mixture contains one kind of molecule. D) Pure substance cannot be separated into any other kind while mixture is a combination of substances. 9. A snake eats a chick that has eaten a worm that has fed on a plant. What trophic level does the plant belong to? · 一 - A) Primary consumer B)Producer C)Secondary consumer D) Tertiary consumer​