What is the nature of the substance with tastes bitter?
Basic
Acids and bases are encountered frequently both in chemistry and in everyday living. Curd, lemon juice, orange juice, and vinegar taste sour. These substances taste sour because they contain acids. The chemical nature of such substances is acidic.
Baking soda, toothpaste, indigestion tablets, etc are bitter in taste. If you rub its solution between fingers, it feels soapy. Substances like these which are bitter in taste and feel soapy on touching are known as bases. The chemical nature of such substances is basic.