Use of amount of substance in relation to masses of pure substances

Question 1

What is a pure substance?

Answer 1

A pure substance consists only of one element or one compound

Question 2

What is mixture?

Answer 2

A mixture consists of two or more different substances, not chemically joined together

Question 3

How can you distinguish between pure substances and mixtures?

Answer 3

Pure substances have a sharp melting point but mixtures melt over a range of temperatures