Q.Which is used to preserve biological specimens ?

A 40% solution of formaldehyde (HCHO) in water is given the common name formalin.

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A ~40% aqueous solution of formaldehyde, called formalin, is used to preserve biological specimens because it denatures and cross-links proteins, killing microbes and hardening tissue.

Formaldehyde (methanal, HCHO) reacts with the amino groups of proteins to form cross-links (via methylene bridges), which denatures the proteins and stops microbial decay. Its aqueous solution, formalin, is therefore widely used in laboratories and museums to preserve biological/anatomical specimens.

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Several common aldehydes are named for their natural plant sources; salicylaldehyde is the one obtained from the meadow-sweet plant.

NCERT lists a few naturally occurring aldehydes and the plants they are obtained from: benzaldehyde from bitter almonds, cinnamaldehyde from cinnamon, vanillin from vanilla beans, and salicylaldehyde from meadow-sweet (Spiraea/Filipendula). …

Formalin, a 40% aqueous solution of formaldehyde, is the standard preservative for biological specimens.

Formaldehyde (methanal, $HCHO$), the simplest aldehyde, is sold commercially as a 40% aqueous solution called formalin. Formaldehyde reacts with the proteins present in living tissue, cross-linking and hardening them (a process called tanning), which prevents microbial decay. Because of this property, formali …

Formalin = ~40% w/v aqueous solution of formaldehyde (HCHO) — option (c).

Formaldehyde gas is very soluble in water; the commercially available and widely used form is an aqueous solution containing about 37–40% HCHO by mass, called formalin. It is used to preserve biological specimens and as a disinfectant/germicide. It is not an alcoho …