Which compound has the longest carbon-carbon bond length? hcch ch3ch3 ch2ch2?

How many moles of magnesium is 3.01 x10^22 atoms of magnesium?

If a solution had a ph of 7 what is the solution

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