Limewater is the common name for a diluted solution of calcium hydroxide. Calcium hydroxide, Ca(OH)2, is sparsely soluble in water (1.5 g/L at 25 °C[1]). Pure limewater is clear and colorless, with a slight earthy smell and an alkaline bitter taste of calcium hydroxide. The term lime refers to the alkaline mineral, and is unrelated to the acidic fruit.
Nickel(II) oxide is the chemical compound with the formula NiO. It is notable as being the only well-characterized oxide of nickel (although nickel(III) oxide, Ni2O3 and NiO2 have been claimed[ The mineralogical form of NiO, bunsenite, is very rare. It is classified as a basic metal oxide. Several million kilograms are produced in varying quality annually, mainly as an intermediate in the production of nickel alloys.
Benzoic acid C7H6O2 (or C6H5COOH), is a colorless crystalline solid and a simple aromatic carboxylic acid. The name is derived from gum benzoin, which was for a long time its only known source. Benzoic acid occurs naturally in many plants and serves as an intermediate in the biosynthesis of many secondary metabolites. Salts of benzoic acid are used as food preservatives and benzoic acid is an important precursor for the industrial synthesis of many other organic substances. The salts and esters of benzoic acid are known as benzoates.