How is a pure substance different from a mixture? a. pure substances cannot be seperated by physical means.
b. a pure substance is heterogeneous.
c. a mixture is made of ine substance.
d. mixtures cannot be seperated by physical means.

Pure substances cannot be separated by physical means.

Explanation:

A pure substance is a substance which contains definite composition of only one type of component. Hence, it cannot be separated by physical means.

On the other hand, a mixture is a substance which contains two or more than two types of components and they can be separated by physical means as well.

Thus, option (a) is correct one that is pure substances cannot be separated by physical means.

it's c. elements are placed in rows based on how may valencies electrons have.

b.

the accuracy of the data.