The element belongs to the p-block. It exhibits some characteristics of metals and some of nonmetals. It is a solid at room temperature. It contains 3d electrons, but not 4d electrons. It is also known NOT to have chemical properties similar to those of nitrogen. The element must be

Arsenic

Explanation:

From the introduction given in the question, the element we are considering must be a member of group 15 because of its similarity to nitrogen.

We were also told that it exhibits the characteristics of metals and some nonmetals hence the element is a metalloid.

Lastly we were told that it contains 3d but not 4d electrons. This has ruled out  antimony. Our only element standing now is arsenic!

The electronic configuration of arsenic is; [Ar] 3d¹⁰ 4s² 4p³. Hence the correct answer is arsenic.

periodic trends is an atom that gets larger as the number of electronic shells increase, the radius of atoms increases as you go down a certain group in the periodic table of elements. in general, the size of an atom will decrease as you move from left to right of a certain period.