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Four successive members of the first row transition elements are listed below with their atomic number. Which one of them is expected to have the highest third ionisation enthalpy ?A. Vanadium (Z=23)B. Chromium (Z=24)C. Iron(Z=26)D. Manganese (Z=25) |
Answer» Correct Answer - D In `._(23)V=1s^(2),2s^(2),2p^(6),3s^(2)3p^(6)3d^(3),4s^(2)` Third electron which is removed in third ionisation potential belongs to `3d^(3)` -subshell. `._(24)Cr=1s^(2),2s^(2),2p^(6),3s^(2),3p^(6)3d^(5),4s^(1)` third electron which is removed in thired ionisation potential belongs to `3d^(3)`-subshell. `._(26)Fe=1s^(2),2s^(2),2p^(6),3s^(2),3p^(6),3d^(6),4s^(2)` Third electron which is removed in third ionisation potantial belong to `3d^(6)`-subshell `._(25)Mn=1s^(2),2s^(2),2p^(6),3s^(2),3p^(6),3d^(5),4s^(2)` Third electron which is removed in third ionisation potential belongs to `3d^(5)`-subshell. In all elements shell and subshell are same . Required amount of energy (enthalpy) is based upon the stability in an ion because it is half-filled subshell (while other are incomplete). So , Mn shows highest third ionisation potential or enthalpy. |
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