Methyl Orange

Please do NOT place your response in a .pdf or .cdx format! I paid a TA last week before I realized that he had ignored my request and placed the response in a .cdx format, which I could not use. If you need to use an attachment in order to respond, please use Word documents. Thanks!

Here's the actual question:

Methyl Orange is an acid-base indicator. In dilute solution, at pH greater than 4.4, it is yellow. At pH=3.2 the solution appears red. Draw a structure of the species that is formed at the lower pH of the acid proton adds to the azo nitrogen atom adjacent to the aromatic ring containing the -SO3 group. Why does the proton add to this particular nitrogen when two other nitrogen atoms are available in the molecule?