Transition and InnerTransition Elements - Result Question 83
####10. The element that usually does not show variable oxidation states is
(2019 Main, 11 Jan I)
(a) $Sc$
(b) $Cu$
(c) $Ti$
(d) $V$
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Solution:
- The most stable oxidation states in the compounds of the given transition metals of $3 d$-series are,
$Sc:+3 ; Ti:+3,+4 ; V:+2,+3,+4,+5 ; Cu:+1,+2$
The electronic configuration of $Sc(Z=21)$ is $[Ar] 3 d^{1}, 4 s^{2}$.
Due to the presence of only one $3 d$-electron
(no pairing energy) and two $4 s$-electrons, they easily ionise to achieve most stable +3 oxidation state.
