7. Consider an electron inside a square quantum well of depth 10eV, and the width of the well is 1nm. What is the ground-state energy? (The zero potential is designated at the bottom of the well. Hint: You can get an estimate from the infinite-well problem.) (A) 0.003eV (B) 0.03eV (C) 0.3eV (D) 3eV (E) 0eV.