Urgent: how is a pure substance different from a mixture?
a. pure substances are separated by physical means
b. mixtures are made up of more than one component
c. a pure substance is heterogeneous
d. mixtures cannot be separated by physical means.

Option (B) is the correct answer.

Explanation:

A pure substance is defined as the substance that contains either same or different type of atoms that are chemically combined to each other in a fixed ratio by mass.

For example, both and are pure substances.

A pure substance can only be separated by chemical means.

Whereas a mixture is defined as the substance that contains two or more different number of substances that are physically mixed together.

For example, salt in water is a mixture.

In a mixture, solute particles can be either evenly or unevenly distributed in the solvent.

A mixture will always be separated by only physical means.

Thus, we can conclude that a pure substance different from a mixture as mixtures are made up of more than one component.

answer: cellular respiration takes in food and uses it to create atp, a chemical which the cell uses for energy. usually, this process uses oxygen, and is called aerobic respiration. it has four stages known as glycolysis, link reaction, the krebs cycle, and the electron transport chain.