Base

First check whether the sample turns red litmus blue or has a pH above 7. Then connect that observation with the idea of hydroxide ions in water. Finally name the sample as a base.

A labelled bottle or beaker sketch can show a red litmus strip changing to blue when dipped into a basic solution.

A common wrong answer is to call a slippery cleaning liquid an acid. That is wrong because slipperiness does not mean acidity; litmus and pH must be checked.

A base is a substance that gives hydroxide ions in water and shows basic behaviour such as turning red litmus blue.

A base is a substance that gives hydroxide ions in water and shows basic behaviour such as turning red litmus blue. Bases give OH^- ions in aqueous solution. In school tests, bases turn red litmus blue and usually have pH above 7. Soap solution is basic. It turns red litmus blue and has a pH above 7.

Bases are the opposite side of the acid-base pair in school chemistry. They usually have pH above 7 and often feel slippery or soapy when dissolved in water. Common examples include sodium hydroxide and soap solution. Bases are important in cleaning, manufacture, and neutralisation reactions. Bases give OH^- ions in aqueous solution. In school tests, bases turn red litmus blue and usually have pH above 7. A student tests soap solution with red litmus. The litmus turns blue, so the sample is identified as a base. This matches the basic behaviour seen in common indicators. Questions usually ask for the correct litmus change, the meaning of pH above 7, or the identification of a basic household solution. A common wrong answer is to call a slippery cleaning liquid an acid. That is wrong because slipperiness does not mean acidity; litmus and pH must be checked.