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.
Alkalis are bases that dissolve in water.
Alkalis are also compounds that react and neutralise acids. They also form a salt and water in the reaction. Alkalis turn red litmus indicator paper blue and they cause Universal Indicator paper to turn blue or purple. Alkaline solutions have a pH valve greater than 7. Alkaline solutions feel soapy and are corrosive.