The statementthat isnot correctfor periodic classification element is

1.	The statementthat isnot correctfor periodic classification element is :
Answer» The propertiesof elementare PERIODICFUNCTION of their atomicnumbers. Non metallicelementsare lessin numberthan metallicelements Fortransition elements the 3d-orbitals are FILLED with electrons after 3P- orbitals and before4s-orbitals Thefirstionisationenthalpies OFELEMENTS generallyincreaseswithincrease in atomicnumberas we goalonga period. Solution :According to aufbau principleenergies of thevariousorbitals increase inthe order `: 1s^(2) ,2 s^(2) 2p, 3s,3p ,4s 3d, 4p……`ETC . Therefore3d- electronsare filled after 4s- andbefore4p-orbitals. Thusoption ( c) isnot correct.

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