<prompt> Percentage of formalin used for histopathological preservative?5102040  <response>: 2Ans. b 10Ref: Handbook of Histopathological and Histochemical Techniques 3rd ed. 40-45 Formalin is generally the preferred fluid for fixation and is widely used. Formalin is often sold as 37-40 aqueous Formaldehyde. To make a solution of 10 Formalin, nine parts of water are added to one part of 40 aqueous Formaldehyde. Therefore, a 10 solution of Formalin is the equivalent of a 4 solution of Formaldehyde. Formaldehyde is a gas produced by the oxidation of methyl alcohol, whereas 100 Formalin is a saturated solution of this gas in water.Other Histopathological Preservatives: Glutaraldehyde: 25-for electron microscopy with osmium tetra-chloride Acetaldehyde acrolein Mercuric chloride Potassium dichromate 