4. * All of the following are found in vehicle exhausts except for one. Which one?
a) Lead
b) Carbon monoxide c) Carbon dioxide d) Hydrogen
A
B
С
D​

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