Always keep in mind while filling any application form that in more than 90 % cases, you always have a chance to upgrade your category from a reserved to a non reserved category but not downgrade i.e., from general to non-reserved. So, if you ever face any such situation, fill the reserved category and if you can't produce the certificate, it will automatically move to general. However, as the application process is over, you can't change it in this form i.e., IISc application form.

Hope this helps.