Solid alkaline hydroxides, lyes, alkalis dissolved in water, e.g. caustic soda, caustic potash. Lyes turn litmus blue particularly irritate the mucous membranes of the eye (caustic soda), saponify fats, oils and resins (to lyes), attack base metals and stain wood dark (smoke).

1. Metal hydroxides - caustic potash Ca (OH)2

2. Alkali hydroxide - caustic soda NaOH - caustic soda KOH

3. Forming without metal - liquid ammonia (ammonia water) NH4OH

4. Aqueous solution of salts - soda-ash Na2CO3 - potash 2CO3