2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/125032Using exact diagonalization we examine the response of several most prominent fractional quantum Hall states to a single local impurity. The 2/3 singlet state is found to be more inert than the polarized one in spite of its smaller incompressibility gap. Based on its spin-spin correlation functions we interpret it as a liquid of electron pairs with opposite spin. A comparison of different types of impurities, non-magnetic and magnetic, is presented.6 pages, 9 figures, submitted to PRBMesoscale and Nanoscale Physicstext