Correct Answer – 3
A superfluid is a most unusual state of matter. Normally atoms are freeto move in a gas ,can move in a more restricted way in a liquid,and can only vibrates about fixed positions in a solid. As the temperature decreases, the amount of thermal motion of atoms decrease and gases become liquids and eventually solids.
At a pressure of `100 kPa` the He gas condenses at `4.2K` to form an ordinary liquid (referred to as helium `I`), but when cooled below `2.2K` the properties of the liquid (now helium II) are dramatically different for example ,helium II has zero viscocity and is an incredibly good thermal conductor ,`10^(6)` times greater than helium `I`.