Question

Name and state the principle which is used to check the purity of milk

Answer 1

Archimedes principle
1 flotation of ships
2 design of hydrometer

Answer 2

"Lactometers" are used to determine the purity of the sample milk. It is an application of Archimedes principle.
Archimedes principle states that " when a body is immersed fully or partially in a fluid, it experiences an upward force that is equal to the weight of the fluid displaced by it."