The statement that is not correct for periodic classification of elements is:
| 1. | The properties of elements are periodic function of their atomic numbers |
| 2. | Non-metallic elements are less in number than metallic elements |
| 3. | For transition elements, the 3d-orbitals are filled with electrons after 3p-orbitals and before 4s-orbitals |
| 4. | The first ionisation enthalpies of elements generally increase with increase in atomic number as we go along a period |
