Answer (2)
Solution: Because the energies of the 5f, 6d, and 7s levels are equivalent, actinoid has a wider variety of oxidation states.
The reason for greater range of oxidation states in actinoids is attributed to (1) Actinoid contraction (2) 
and 
levels having comparable energies (3) 
and 
levels being close in energies (4) The radioactive nature of actinoids
and levels having comparable energies (3) and levels being close in energies (4) The radioactive nature of actinoidsThe reason for greater range of oxidation states in actinoids is attributed to (1) Actinoid contraction (2) and levels having comparable energies (3) and levels being close in energies (4) The radioactive nature of actinoids
and levels having comparable energies (3) and levels being close in energies (4) The radioactive nature of actinoids![\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{-2}](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-c5a91864ba7e1e0ed1b5d273d822f5e5_l3.png "Rendered by QuickLaTeX.com")
(b) ![\left[\mathrm{Pd}(\mathrm{CN})_{4}\right]^{2-}](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-ffda616d3dbe7dc8925722e87005924e_l3.png "Rendered by QuickLaTeX.com")
(c) ![\left[\mathrm{PdCl}_{4}\right]^{2-}](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-90cc6a4f4d42dee46e06d6f8ed516b7a_l3.png "Rendered by QuickLaTeX.com")
(d) ![\left[\mathrm{NiCl}_{4}\right]^{2}](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-149ee5c95bd9cfcc4405704fba2e1bab_l3.png "Rendered by QuickLaTeX.com")
(d) all of these