Here are four characteristics of acid: a) A characteristic sour taste b) ability to change the color of litmus paper from blue to red c) react with certain metals to produce gaseous H2 d) react with bases to form a salt and water Solution Here are four characteristics of acid: a) A characteristic sour taste b) ability to change the color of litmus paper from blue to red c) react with certain metals to produce gaseous H2 d) react with bases to form a salt and water.