Ammonia, NH 3, is an alkaline gas and so turns damp red litmus paper blue. Ammonium ions (NH ... of the ions with sodium hydroxide. This reaction produces ammonia gas, as shown in the ionic ...

You remember: you’d dip a bit of pinkish litmus paper into some liquid and watch for the reaction. “Acidic” is a probably good way to describe the way Donald Trump is treating Canada these days.

Damp litmus paper is bleached white when it is placed in chlorine. If damp-blue litmus paper is used, the paper turns red then white.