How do scientists build on previous work when developing theories

What is the independent variable in this investigation? mass volume sample number substance density

The bond energy for the van der waals bond between two helium atoms is 7.9×10−4ev. assuming that the average kinetic energy of a helium atom is (3/2)kbt, at what temperature is the average kinetic energy equal to the bond energy between two helium atoms

What are the two largest greenhouse gases