Before spectroscopy was invented, Korner's absolute method had been used to determine whether a disubstituted benzene derivative was the ortho, meta, or para isomer. Korner's method involves adding a third group (often a nitro group) and determining how many isomers are formed. A turn-of-the-20th-century chemist isolated an aromatic compound of molecular formula C6H4Br2. He carefully nitrated this compound and purified three isomers of formula C6H3Br2NO2, one of which was obtained in very small amounts. Propose a structure for the original compound.

Answer is explained in the explanation section below.

Explanation:

Definitely, before the invention of spectroscopy, Korner's absolute method had been in use. So, the proposed structure is a diagram, that we can not draw here. Therefore, I have drawn it separately and attached in the attachment below. Please for this answer, refer to the diagram which is a proposed structure attached in the attachment below.

Proposed Structure is:

1,3-Dibromo Benzene.

In the Korner's method, 1,3- Dibromo benzene undergoes nitration process in the presence of HNO3/H2SO4.

The original compound that undergoes nitration is a meta disubstituted aromatic compound.

After nitration, 1,3-Dibromo benzene yields three having chemical formula C6H3Br2NO2.

assuming that your periodic table has eighteen columns, you should highlight   the four elements in the third column from the left of the table.

neutral atoms of elements after calcium contain d electrons. the energy of d orbitals of a particular main shell lies between the energy of the s and p orbitals of the next main shell. for example, electrons in the have energy higher than those in the orbital while lower than those of the orbital.

by the aufbau principle, electrons fill orbitals one at a time, starting from those of the lowest energy. the orbital is therefore filled right after orbitals and before orbitals.  

potassium has electron configuration and calcium . the s orbital of a main shell holds a maximum of two electrons. the next element would thus have the electron configuration and satisfy the requirements.

a neutral atom of the element contains three electrons on top of the most recent noble gas element. it should thus be placed in the third column of the periodic table. both scandium and yttrium would satisfy the conditions. an aufbau diagram indicates that the 4f orbital is filled before the 5d. however, it appears that exceptions exists for both lanthanum and actinium. neutral atoms of the two d-block elements also demonstrate the and should be highlighted as well.

6.4 cm (max) - 25 cm (min)