The group number of the element in the periodic table with the electronic configuration ( n -1) d ^2 ~ns ^2 . For n=4 is:

Step-by-step solution

The given electronic configuration is (n-1)d^2 ns^2 . For n=4 , the configuration becomes (4-1)d^2 4s^2 , which is 3d^2 4s^2 . This element is Titanium (Ti), which has an atomic number of 22. For transition elements (d-block elements), the group number is determined by the sum of electrons in the (n-1)d subshell and the ns subshell. Group number = (number of electrons in (n-1)d ) + (number of electrons in ns ). Group number = 2 + 2 = 4 . Therefore, the element belongs to Group 4. Answer: 4