Question

out of the elements cr(z-24) Mg(z-12) and Fe(z-26) identify the element with 5 electron in the 3 d sub shell​

Answer 1

Let us see the electronic configuration of these elements Electronic configuration of Cr = [Ar] 3d54s1 Electronic configuration of Mg = [Ne] 3s2 Electronic configuration of Fe = [Ar] 3d6 4s2 Chromium is the elemet with 5 electrons in its 3d orbital

Answer 2

So out of above elements Cr(z=24) is the element with 5-electrons in 3d-orbital. .