Which of the following is NOT a physical or chemical characteristics of interstitial compounds?

Pairs of elements with the same number of electrons in their respective 4f orbital are

[Atomic number. Eu-63, Gd-64, Dy-66, Ho-67, Tm-69, Yb-70, Lu-71, Hf-72]

A. (Eu and Gd)

B. (Dy and Ho)

C. ( Yb and Hf )

D. ( Lu and Tm)

Choose the correct answer from the options given below :

Consider $|x|$ is the difference in oxidation states of Mn in highest manganese fluoride and highest manganese oxide. The ions with $|x|$ number of unpaired electrons from the following are :

A. $\mathrm{Sc}^{3+}$

B. $\mathrm{Zn}^{2+}$

C. $\mathrm{V}^{2+}$

D. $\mathrm{Fe}^{2+}$

E. $\mathrm{Co}^{2+}$

Choose the correct answer from the options given below :

The correct statements among the following are,

A. $\mathrm{Mo}(\mathrm{VI})$ and $\mathrm{W}(\mathrm{VI})$ are less stable than $\mathrm{Cr}(\mathrm{VI})$.

B. $\mathrm{Ce}^{4+}$ and $\mathrm{Tb}^{4+}$ are oxidant while $\mathrm{Eu}^{2+}$ and $\mathrm{Yb}^{2+}$ are reductant.

C. Cm and Am have seven unpaired electrons.

D. Actinoid contraction is greater from element to element than lanthanoid contraction.

Choose the correct answer from the options given below :