Question

Formalin is an aqueous solution of

• A. fluorescein
• B. formic acid
• C. formaldehyde
• D. furfuraldehyde

Answer 1

Answer: (C)

The $40\%$ solution of formaldehyde in water is sold in market under the name of formalin. Formaldehyde in the form of formalin ($40\%$ formaldehyde, $8\%$ methanol and $52\%$ water) is used for preserving biological specimens.
Formalíne solution also used as a disinfectants and commonly used in hardeness and nail varnish.