There are generally two ways any molecule or atom is excited. It either is given heat (by you), or it gets hit with ultraviolet (UV) light (from the sun). In most cases, this is enough to promote the electron to the higher orbital. I am not sure that the hydrogen atom can just excite the electron to jump up to the 2p orbital, I would be inclined to say that it is because of heat or ultraiolet light.
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