उत्तर : 3. "प्रायिकता घनत्ब शून्य हो जाये"
व्याख्या :

A nodal surface, also called a radial node, is a hollow spherical region that cannot contain electrons. A nodal plane is also called an angular node, which is either a plane where electrons cannot occur, or a conical surface (d z 2 orbital).