Discuss the properties of Helium 1 & Helium 2. What do you understand by lamda point?

Answer 1

I think you mean Helium-3 (isotope) and Helium-4.

It's quite complex and goes into superfluidity below the lambda point.

Read more here, quite a good description....
http://hyperphysics.phy-astr.gsu.edu/hbase/lhel.html

Interestingly, Helium-3 can never become solid due to the 'latent heat' taken in during the phase change from liquid to solid - is actually enough to keep the Helium-3 as a fluid and stops it becoming as solid.