The hydroxides formed in all of these reactions dissolve in water to form Having a pH greater than 7. solutions. These solutions turn Paper stained with universal indicator, a chemical solution that produces many different colour changes corresponding to different pH levels. purple, showing they are strongly alkaline. Strong alkalis are Able to damage metal, stonework, clothes and skin. Strong acids and alkalis are corrosive.. Care must be taken when they are used – goggles and gloves should be worn.
