The valence shell of the element X contains 1electron in 5s subshell and, below that shell, 4 electrons in 4d subshell. The element belongs to which group (IUPAC) of periodic table?

The valence shell of the element X contains 1electron in 5s subshell and, below that shell, 4 electrons in 4d subshell.. So,

$5s^{1}4d^4$

Rearranged order,

$5{\mathrm{s}}^2{\mathrm{d}}^3$

It is a transition element of d-block and belongs to 5th group as,

$3+2=5$