Outermost electronic configuration of a group 13 element, E, is 4s², 4p¹. The electronic configuration of an element of p-block period-five placed diagonally to element, E is :

Solution

Chemistry ma’am · 3 steps

Diagonal means one step down and one step right: from Ga in period 4, group 13, you land on Sn.

1. Identify E. The valence shell is n = 4, so E is in period 4. It has three valence electrons, 4s² 4p¹, so it is in group 13. That is gallium, Ga.
2. Move diagonally. The diagonal partner sits one period down and one group to the right. So you need the period 5, group 14 element, which is tin, Sn. Its valence shell is 5s² 5p², with a filled 4d¹⁰ just below it.

   Option	Element	Period, group	Diagonal to Ga?
   (a) [Kr] 3d¹⁰ 4s² 4p²	not a real configuration	the Kr core already holds 3d¹⁰ 4s² 4p⁶	no
   (b) [Ar] 3d¹⁰ 4s² 4p²	Ge	4, 14	no, it sits beside Ga
   (c) [Xe] 5d¹⁰ 6s² 6p²	Pb	6, 14	no, two periods down
   (d) [Kr] 4d¹⁰ 5s² 5p²	Sn	5, 14	yes

3. So. The period 5 p-block element diagonal to gallium is tin, [Kr] 4d¹⁰ 5s² 5p². The answer is (d).

The idea to keep. Read the period from the highest n and the group from the valence electrons. Then a diagonal partner is always one period down and one group to the right.

Answer from the NTA final answer key. Solution by PrepWiser.