NEET Test Series from KOTA - 10 Papers In MS WORD
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CHXII08:THE D- & F-BLOCK ELEMENTS
321676
The reason for greater range of oxidation states in actinoids is attributed to :
1 actinoid contraction
2 \({\rm{5f,}}\,\,{\rm{6d}}\,\,{\rm{and}}\,\,{\rm{7s}}\) levels having comparable energies
3 \(\mathrm{4 \mathrm{f}}\) and \({\rm{5d}}\) levels being close in energies
4 the radioactive nature of actinoids
Explanation:
Minimum energy gap between 5f, \({\rm{6d}}\,\,{\rm{\& }}\,\,{\rm{7s}}\) subshell. Thats why \(\mathrm{e^{-}}\)excitation will be easier.
NEET - 2017
CHXII08:THE D- & F-BLOCK ELEMENTS
321677
Which of the following actinoids exhibits only +3 oxidation state?
1 \(\mathrm{\operatorname{Lr}(Z=103)}\)
2 \(\mathrm{U(Z=92)}\)
3 \(\mathrm{\operatorname{Th}(Z=90)}\)
4 \(\mathrm{\mathrm{Pa}(\mathrm{Z}=91)}\)
Explanation:
Lawrencium (Lr) shows only +3 oxidation state, that has electronic configuration \(\mathrm{[\mathrm{Rn}] 5 \mathrm{f}^{14} 7 \mathrm{~s}^{2} 7 \mathrm{p}^{1}}\). This element may easily give up three valence electron from the \(\mathrm{7 \mathrm{~s}}\) and \(\mathrm{7 \mathrm{p}}\) subshell to form a stable +3 oxidation state. The state is especially stable in case of \(\mathrm{\mathrm{Lr}}\) because it contain full filled \(\mathrm{\left(5 f^{14}\right) \mathrm{f}}\) - subshell.
321676
The reason for greater range of oxidation states in actinoids is attributed to :
1 actinoid contraction
2 \({\rm{5f,}}\,\,{\rm{6d}}\,\,{\rm{and}}\,\,{\rm{7s}}\) levels having comparable energies
3 \(\mathrm{4 \mathrm{f}}\) and \({\rm{5d}}\) levels being close in energies
4 the radioactive nature of actinoids
Explanation:
Minimum energy gap between 5f, \({\rm{6d}}\,\,{\rm{\& }}\,\,{\rm{7s}}\) subshell. Thats why \(\mathrm{e^{-}}\)excitation will be easier.
NEET - 2017
CHXII08:THE D- & F-BLOCK ELEMENTS
321677
Which of the following actinoids exhibits only +3 oxidation state?
1 \(\mathrm{\operatorname{Lr}(Z=103)}\)
2 \(\mathrm{U(Z=92)}\)
3 \(\mathrm{\operatorname{Th}(Z=90)}\)
4 \(\mathrm{\mathrm{Pa}(\mathrm{Z}=91)}\)
Explanation:
Lawrencium (Lr) shows only +3 oxidation state, that has electronic configuration \(\mathrm{[\mathrm{Rn}] 5 \mathrm{f}^{14} 7 \mathrm{~s}^{2} 7 \mathrm{p}^{1}}\). This element may easily give up three valence electron from the \(\mathrm{7 \mathrm{~s}}\) and \(\mathrm{7 \mathrm{p}}\) subshell to form a stable +3 oxidation state. The state is especially stable in case of \(\mathrm{\mathrm{Lr}}\) because it contain full filled \(\mathrm{\left(5 f^{14}\right) \mathrm{f}}\) - subshell.