Assertion: In transition elements radii of 5d series are virtually the same as those of the corresponding members of 4d series. Reason: The filling of 4f orbitals before 5d orbitals results in regular decrease in atomic radii.

Question

Assertion: In transition elements radii of 5d series are virtually the same as those of the corresponding members of 4d series. Reason: The filling of 4f orbitals before 5d orbitals results in regular decrease in atomic radii. (A) If both assertion and reason are true and reason is the correct explanation of assertion (B) If both assertion and reason are true but reason is not the correct explanation of assertion (C) If assertion is true but reason is false (D) If both assertion and reason are false

Tardigrade Admin · Accepted Answer

It is the phenomenon occurring in the 3 rd series of transition element. As they have electron filling up the 4 f shell which is filled with the 5 d series. The 4 f shell has very weak sheillding effect and is highly attracted towards the nucleus due to high nuclear charge so the filling of 4 f orbitals before 5 d orbital resulting in their atomic radius which is very similar to the elements of the 2 text nd series i.e, Zr =160 atomic radius and Hf =159 atomic radius.

Q. Assertion : In transition elements radii of 5d series are virtually the same as those of the corresponding members of 4d series. Reason : The filling of 4f orbitals before 5d orbitals results in regular decrease in atomic radii.

If both assertion and reason are true and reason is the correct explanation of assertion

If both assertion and reason are true but reason is not the correct explanation of assertion

If assertion is true but reason is false

If both assertion and reason are false

Q. Assertion : In transition elements radii of $5 d$ series are virtually the same as those of the corresponding members of $4 d$ series.
Reason : The filling of $4 f$ orbitals before $5 d$ orbitals results in regular decrease in atomic radii.