wavelength of light in nanometers emitted when an electron in the n=5 level of hydrogen relaxes to the n=3 level?

The molecular formula for caffeine is cshion402. which of the following elements is not found in caffeine?

The blackbody curve for a star name zeta is shown below. what is the peak wavelength for this star ?

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