Question

Which of the following pairs has almost the same colors?
A) $_{60}N{d^{3 + }}{._{69}}T{m^{3 + }}$
B) $_{70}Y{b^{3 + }}{,_{59}}P{r^{3 + }}$
C) $_{63}E{u^{2 + }}{,_{67}}T{b^{3 + }}$
D) $_{64}G{d^{3 + }}{,_{67}}H{o^{3 + }}$

Answer 1

We know that the components comprising the f-block are those wherein 4f and 5f orbitals are dynamically filled. These components are formal individuals from bunch 3 yet are shown independently as f-square of the occasional table. The components of f-block are additionally called internal progress components. The two arrangements of internal progress components that are $4f$ and $5f$ arrangements are known as Lanthanides and actinides individually. The inward progress components, for example,$U$, $Th$ and $Pa$ are giving acceptable wellsprings of thermal power.

Complete answer:
We know that europium is a compound with nuclear number $63$. Europium is the most responsive lanthanide by a wide margin, being put away under a dormant liquid to shield it from barometrical oxygen or dampness. Europium is additionally the gentlest lanthanide, as it tends to be imprinted with a fingernail and effortlessly cut with a blade. At the point when oxidation is taken out a sparkly white metal is apparent. The electronic configuration of $Eu$ is $\left[ {Xe} \right]4{f^7}$.
Terbium is a compound with nuclear number $65$ . It is a shimmering white, uncommon earth metal that is pliant, pliable, and sufficiently delicate to be cut with a blade. The 10th individual from the lanthanide arrangement, terbium is a genuinely electropositive metal that responds with water, developing hydrogen gas. The electronic configuration of $Tb$ is $\left[ {Xe} \right]4{f^8}$.
The two of them have practically the same number of electrons for the change, so they show the practically same color.

Henceforth, choice C is right.

Note:
Fundamental Characteristics of Inner Transition Elements:
In the inward progress components the third last shell is loaded up with electrons.
The internal change components structure shaded particles.
The internal change components show variable valencies.
Actinides are ordinarily radioactive.
The inward change components past nuclear number $92$ up to $103$ are engineered just as radioactive. They are not found in nature outside.