What percentage of formaldehyde is present in formalin?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 40%
NCERT (2026-27 edition):
8.5 Uses of Aldehydes and Ketones – “… Formaldehyde is well known as formalin (40%) solution used to preserve biological specimens and to prepare bakelite (a phenol-formaldehyde resin), urea-formaldehyde glues and other polymeric products.”