How will you prove that a given colourless liquid is an acid

Explanation:

One: You could mix a small sample of it with a reactive metal. Underline small. You should see gas bubbles being given up. Usually the bubbles are hydrogen.

Example : K + HCl ===> KCl + H2

Two: You could use an indicator to watch it turn color as it goes from acidic to neutral. Litmus will go from red to blue under these conditions.

Three: Those are the two safest ways. If you knew the acid was dilute, you could put a small (underline small again) amount on your tongue. If it tastes like orange juice, it is likely an acid. This is a test every textbook mentions. You should never do it under any circumstances.