How is 0.00069 written in scientific notation?

In an exothermic reaction the bonding energy of the product is: less than the reactants same as the reactants greater than the reactants dependent upon the presence of a catalyst

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 type of matter is made of only one kind of atom