Question

The percentage of formaldehyde in formalin is:
A. 40%
B. 30%
C. 20%
D. 10%

Answer 1

Hint: Percentage of solvent: It is defined as the ratio of the volume or the mass of the chemical compound per ml of solution.
\[\]$ \Rightarrow \dfrac{{volume}}{{ml{\text{ }}of{\text{ }}solution}}$ Or
 $ \Rightarrow \dfrac{{volume}}{{ml{\text{ }}of{\text{ }}solution}}$

Complete step by step answer: Formaldehyde: It is a strong pungent smelling colourless organic substance. It belongs to the category of aldehydes and is a simpler form having chemical formula $C{H_2}O$. When in its gaseous state it polymerizes to form paraformaldehyde that is why it is stored in aqueous solution.
Use of formaldehyde:
It has its major application in laboratories as preservative for tissue.
When an individual comes in contact with formaldehyde, it creates a burning sensation in the nose, eyes, throat and individual experiences watery eyes and congestion in the throat.
Formalin: It is a by-product of formaldehyde produced when 37% by weight or 40% by volume of formaldehyde is mixed with water containing 10-15 methanol.
Effect of formalin:
Research has proved that scholars or scientists working in laboratories having high exposure to formalin, has high risk of developing leukaemia which is a blood cancer, hence it is categorised as a carcinogen.
Hence after studying about the preparation procedure of formalin from formaldehyde, we come to know that 40% of formaldehyde is present in formalin.
So, the correct answer is “Option A”.

Note: The application of formalin is to be used as disinfectant, preservative and antiseptic in hospitals and in common places such as homes, schools, in medical rooms but as preservative it issued only in histology labs to preserve tissues for further experiments or for future testing of the samples collected.