Ahydrogen atom, whose normalized stationary state is described by inlm), where n is the main quantum number and l and m is the quantum numbers belonging to l and lz: nim as usual the following operators is introduced here we neglect spin and fine structure a hydrogen atom is descripted by the normalized wave function b) (|210) + |211)) find the mean of lz in the state 14). account for the fact, that around the standard deviations on the observables lx and ly the following must be the case 1.