Question

5th period transition elements resembles in the chemical properties with 4th period

transition elements due to
​

Answer 1

It is due to the similarity in size.

Explanation:

Fifth-period transition elements have d and f electrons that are supposed to provide the least screening effect and thus, reducing the size of atoms.

The decrease in size is so much, that the sizes become similar to that of the 4d transition elements.

It is well known that elements with similar sizes show similar properties - physical as well as chemical.

Hence, this similarity is observed.