Solution

The $$d$$- block elements that are the elements from the group $$3-12$$ are called transition elements. The position of d-block elements is in between s−block and p−block elements in the periodic table. These d-block elements are called transition elements because they exhibit transitional behavior between s− and p−elements.
Their properties are transitional between highly reactive metallic elements of s−block which are typically ionic compounds and elements of p−block which are large - covalent.
The first main transition series begins with either scandium (symbol Sc, atomic number 21) or titanium (symbol Ti, atomic number 22) and ends with zinc (symbol Zn, atomic number 30).
The second series includes the elements yttrium (symbol Y, atomic number 39) to cadmium (symbol Cd, atomic number 48).
The third series extends from lanthanum (symbol La, atomic number 57) to mercury (symbol Hg, atomic number 80). These three main transition series are included in the set of 30 elements often called the d-block transition metals.