The 1996 Nobel Prize in Physics was awarded to Douglas Osheroff, Robert Richardson, and David Lee for discovering superfluidity (apparently frictionless flow) in 3 He. When 3 He is cooled to 2.7 mK, the liquid settles into an ordered superfluid state. Predict the sign of the entropy change for the conversion of liquid 3 He into its superfluid state.

As it is known that entropy is the degree of randomness of the molecules of a substance or object.

When particles or molecules of a substance are placed in orderly manner then it means that there is low entropy. But when molecules are randomly moving then it means the system is in disorder and will have high entropy.

Since, molecules of a solid are orderly arranged. Therefore, solid substances have very low entropy.

Liquid molecules have the ability to slide past each other. Hence, liquids have moderate entropy whereas gas molecules are held by weak intermolecular force.

So, molecules of a gas move much more rapidly and hence, they have high entropy.

As it is given that 3 He is cooled to 2.7 mK, and the liquid settles into an ordered super-fluid state.

Therefore, there will occur a decrease in entropy.

Thus, we can conclude that the sign of entropy for the given case is negative.