Final answer:
Formalin is a mixture of buffered water and formaldehyde. The percentage of formaldehyde in formalin can be calculated by dividing the volume of formaldehyde by the total volume and multiplying by 100.
Step-by-step explanation:
Formalin is a mixture of buffered water and formaldehyde. It is commonly sold as a 37% to 40% aqueous solution. This means that in every 100mL of formalin, 37mL to 40mL is formaldehyde. To express this as a percentage, you can calculate it by taking the volume of formaldehyde and dividing it by the total volume and then multiplying by 100. For example, if the formaldehyde volume is 37mL in a 100mL solution, the percentage of formaldehyde would be 37%.