42. Interstitial compounds are formed when small atoms are trapped inside the crystal lattice of metals. Which of the following is not the characteristic property of interstitial compounds?

(A) They have high melting points in comparison to pure metals

(B) They are very hard

(C) They retain metallic conductivity

(D) They are chemically very reactive.

Electronic configuration of

Gd is ; Gd₆₄ = [Xe]4f⁷ 5d¹ 6s²

Hence $G{d}_{64}^{++}=\left[Xe\right]4f^{7}5d^{1}6s^0$

Total number of electrons in 4f sub-shell = 7

Ans. = 7

Molecular formula of Mohr’ salt, FeSO₄. (NH₄)₂SO₄.6H₂O.

Molecular formula of potash alum = K₂SO₄.Al₂ (SO₄)₃.24H₂O. Overall molecular formula of potash alum = KAl (SO₄)₂. 12H₂O. Ratio of water molecules in Mohr’ salt and Potash alum

$=\frac{6}{12}=\frac{1}{2}=0.5=5\times 10^{-1}$       

Ans. = 5

Cu₂Cl₂ + Water -> Insoluble

AgCl + Water -> Insoluble

ZnCl₂ + Water -> Colouless solution

CuCl₂ + Water -> Coloured solution due to 3d⁹ electronic configuration.

Nucleophilicity is directly proportional to the electron density of atom and inversely proportional to its electronegativity.

According to Ellingham diagram, the metal oxide with lower $\Delta G^o$ is more stable than metal oxide of higher $\Delta G^o$ at same temperature.