An element has a configuration:   [ Ar ]   3 d 3 4 s 2 , predict the group or period of the…

The electronic configuration is given as $\left[\mathrm{Ar}\right] 3{\mathrm{d}}^{3}4{\mathrm{s}}^2$. In this electronic configuration sum of the number of valence electrons is equal to the group number and the highest value of principal quantum number is equal to period number. Its atomic number is 18(Ar)+5(valence electrons)=23. Hence, It is Vanadium element. It is located in 4th period and 5th group of the periodic table.