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