What do you mean by pure substance how would you confirm that a colourless liquid given to you is a pure water?

What do you mean by pure substance how would you confirm that a colour

1.	What do you mean by pure substance how would you confirm that a colourless liquid given to you is a pure water?
Answer» Pure substances are DEFINED as substances that are made of only one TYPE of atom or molecule. if that colourless liqiud starts boiling exactly at 100°C then it is water BCOS other colourless liquids like vinegar donot BOIL exactly at 100°C. another way is by TESTING it with pH paper, if its colour remains same it is water bcos pH of water is 7 which is nuetral.. hope it helps u..