5.
Which of the following statements is .true.?
(A) We can determine the exact location of an electron if we know its energy.
(B) Ni has 2 unpaired electrons in its 3d orbitals in its ground state.
(C) An electron in a 2s orbital can have the same n, l, and m_l quantum numbers as an electron in a 3s orbital.
(D) Only three quantum numbers are needed to uniquely describe an electron.
(E) In the building up of atoms, electrons occupy the 4f orbitals before the 6s orbitals.