Bases react with acids to form salt and water. Bases include insoluble metal oxides and insoluble metal hydoxides. Alkalis are group 1 and group 2 soluble hydroxides. These soluble hydroxides are NaOH, LiOH, KOH, Ca(OH)2, Sr(OH)2, Ba(OH)2 and the only other alkali (which we need to know) is the ammonium hydroxide NH4OH.
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