Question

Formalin is ____% solution of formaldehyde is water.
A. 10
B. 20
C. 40
D. 60

Answer 1

Hint: The 100 % saturated solution of formalin is prepared by dissolving formaldehyde in water. It can be either done by weight percentage or by volume percentage. The 100 % solution of formalin contains 60 % of solvent in it.

Complete step by step answer: Formaldehyde is a gas with a very strong pungent odour. It is the simplest and first aldehyde with the chemical formula HCHO. Formaldehyde is formed by the oxidation of methanol. It is used as an antiseptic and disinfectant. Formaldehyde readily dissolves in water. The formaldehyde is often used as 37-40% that means that the gas is dissolved in the water to attain the saturation point within this concentration. The concentration of the formaldehyde depends on the technique whether the saturation point is measured by weight percentage (37%) or by volume percentage (40%).
Formalin is defined as the solution of formaldehyde dissolve in water. The saturated solution of formaldehyde dissolved in water is known as stronger formalin than is 100% formalin or saturated formalin.
The saturated formalin is 40 % formaldehyde and 60% water forming a 100 % solution. It is calculated by volume percentage.
Thus, Formalin is 40 % solution of formaldehyde is water.
So, the correct answer is “Option C”.

Note:
A 10% solution of formaldehyde in water is used as a disinfectant and helps in preserving the specimens in the laboratory. Formaldehyde is also known as methanal, methyl aldehyde, methylene oxide, iodomethane and oxymethylene.