How would you confirm that a colourless liquid given to you is pure water?

Question 6. How would you confirm that a colourless liquid given to you is pure water?
Answer: Take a sample of colourless liquid and put on stove if it starts boiling exactly at 100 ºC then it is pure water. Any other colourless liquid such as vinegar always have different boiling point. Also observe carefully that after some time whole liquid will convert into vapour without leaving any residue.