What is the wavelength of an electro magnetic wave has a frequency of 1.82×10 to the 18th Hz in a vacuum

How are isotopes of the same chemical element alike? how are they different?

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

Which of the following is a chemical property of water at 4 c