Class 12th

ln $Cul,C{u}^{+}has3d^{10}4s^0,\left[n=0and\mu =0BM\right]$

ln   $\left[Cu{\left(N{H}_3\right)}_4\right]C{l}_2,C{u}^{++}has3d^{9}4s^0\left[n=1and\mu =1.73BM\right]$

$ln{O}_2^{-}\&{O_2}^{+}$ only one electron is unpaired in anti bonding MO,

Hence [n = 1 and $\mu$ = 1.73 BM]

$K_2\left[Ni{\left(CN\right)}_4\right]$

$N{i}^{2+}\to 3d^{8}4s^0$

dsp² hybridisation

Paring developed due to strong ligand effect.

NiCl₂.6H₂O

Ni²⁺ ->3d⁸4s⁰

Na₂ [NiCl₄]

Ni²⁺ -> 3d⁸4s⁰

[Ni (CO)₄]

Ni->3d⁸4s²

Option C describes both water and air pollution clearly in the statement as the root cause of the change in the color of the stonework of the Taj Mahal.

Tyndall effect is the optical characteristics of light in which comparable particle size of colloids and bombarded light wavelength can produce this type of effect. For scattering effect of light in Tyndall effect refractive index of dispersed phase and dispersion medium should be greatly different.

Due to volatile nature, Zn – metal can be economically purified by fractional distillation refining process.