You may have met some of the information in other Revision Bites. The examples used will be different. Each area is quite small. Part one needs to be visited first and then you can select any of the other areas. An acid is a compound that contains hydrogen and when it is dissolved in water the solution has a pH of less than 7.
Acids turn blue litmus indicator paper red.
Universal Indicator paper changes colour to yellow, orange or red in an acidic solution. Acids will react with the following chemicals and these will neutralise the acid. Alkalis A base is a compound that reacts and neutralises an acid. The reaction forms a salt and water. Alkalis are a type of base.