Hi Sudam,

It depends on the notification of the concerned area/organisation/exam where you wish to apply. If they have mentioned it by quoting your branch's name, only then you can apply. Otherwise, you cannot consider yourself as a chemical student on your own. Generally, what happens students take the concerned exams or apply in different areas without taking care of the exact requirement mentioned. Unfortunately, at the time of document verification, they get eliminated. So please go through each notification carefully as the consideration differs. 
Hope this helps.