d and f Block Elements

Assertion : \(d^5\) configuration is more stable than \(d^4\).
Reason : \(d^5\) has more exchange energy as compared to \(d^4\) because 10 and 6 exchanges are possible in \(d^5\) and \(d^4\) respectively.

Assertion : \(\mathrm{Yb}^{2+}\) is more stable in compare to \(\mathrm{Gd}^{+2}\).
Reason : The electronic configuration of GD is \([\mathrm{Xe}] 4 f^7 5 d^2 6 s^2\).

Assertion : \(\mathrm{S}_2 \mathrm{O}_7^{2-}\) and \(\mathrm{Cr}_2 \mathrm{O}_7^{2-}\) both exist.
Reason : Both have same valence electrons.

Assertion : Out of \(\mathrm{CrO}_3\) and \(\mathrm{Al}_2 \mathrm{O}_3, \mathrm{CrO}_3\) having lower melting point than \(\mathrm{Al}_2 \mathrm{O}_3\).
Reason : Oxidation state of \(\mathrm{Cr}\) in \(\mathrm{CrO}_3\) is high.

Which give coloured carbonate precipitate?

Which element can have oxidation state
from 4 to 6?

Assertion (A) Separation of Zr and Hf is
difficult.
Reason (R) Zr and Hf lie in the same group
of the periodic table.

The correct order of spin only magnetic moment (in BM) for \(\mathrm{Mn}^{2+}, \mathrm{Cr}^{2+}\) and \(\mathrm{Ti}^{2+}\) ions is