Question

Which of the following is the highly unstable​

Answer 1

Answer:

see down

Explanation:

highly unstable species is co(

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Answer 2

Answer:

The correct answer is (a) $\text{Sc} \mathrm{(II)}$

Scandium is highly unstable in the (+2) oxidation state.

Explanation:

• The electronic configuration of Scandium (atomic number-21) is:
  $\bold{1s^{2} \ 2s^{2}\ 2p^{6} \ 3s^{2} \ 3p^{6}\ 3d^{1} \ 4s^{2}}$  or  $\bold{[Ar]\ 3d^{1} \ 4s^{2}}$
  

• The electronic configuration of $\text{Sc} \mathrm{(II)}$ will be:
  $\bold{1s^{2} \ 2s^{2}\ 2p^{6} \ 3s^{2} \ 3p^{6}\ 3d^{1}}$  or  $\bold{[Ar]\ 3d^{1}}$
  The configuration has a single electron in $\bold{3d}$ orbital is appeared to be unstable.
  

• Therefore, Scandium is found in the +3 oxidation state (Noble gas configuration) rather than the +2 oxidation state.
  

• In general, the relative stability of the first transition series consisting $\bold{+2}$ oxidation state increases on moving left to right.
  
• This is due to the decrease in atomic radius from Scandium to Zinc, which results in the increase in nuclear charges through the series.
  

To summarize, $\text{Sc} \mathrm{(II)}$ Scandium in $\bold{+2}$ oxidation state is highly unstable.