Which of these is true about pure substances?

a. they can only contain one type of atom

b. they can only contain one type of molecule

c. they may contain one type of atom or one type of molecule

d. they can contain different types of atoms and molecules

They can only contain one type of atoms, one type of molecules or one type of ionic salts

Explanation:

Remember that substances might be made of:

That said, pure substances would only contain one type of atoms, one type of molecules or one type of ionic salts. Any additional components of different atoms, molecules or ionic salts would cause a pure substance to become a mixture of several substances.

the answer is:  

line graphs show patterns in data with variables that change over time; whereas, circle graphs show data as parts out of a whole (such as out of 100%).

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