An element X belongsto fourthperiod and fifteengroupof theperiodic table .Which of thefollowingstatements is true?

An element X belongsto fourthperiod and fifteengroupof theperiodic tab

1.	An element X belongsto fourthperiod and fifteengroupof theperiodic table .Which of thefollowingstatements is true?
Answer» It has acompletelyfilled s- orbital and apartially filledd- orbital It hascompletely filled s- orbitaland a partially filledd- orbital It hascompletely filled s- and p- ORBITALS anda half filledd- orbital It hasa half filledp- orbital andcompletelyfilled s-and d-orbitals . Solution :Inthe 4thperiod, threesubshells(i.e.,4s , 3d , 4p) are propressivelyfilled in orderof increasingenergy`(4s lt 3d lt 4p) .` Afterfilling4s- subshellwith 2electrons3d-subshellwith 10 electrons the FILLINGOF 4p- subshellbeginswithelements withZ= 31- 36. In the15thperiod, three4p- orbitalsare completelyhalf- filled. Thusthe atomicnumberof the elementwiththreehalf- filled4p-orbitalsis 33 and its nameis As andits outerelectronicconfigurationis `[Ar] 4s^(2)3d^(10)4p_(X) 4p_(y) 4p_(z)` Inotherwordsthe elementhas half- filledp- orbitalsand completelyfilled s- andd- orbitals i.e.,option( d) iscorrect.