In this situation an English speaker would interchange "may" or "can." I don't think a good argument can be made that it should be strictly "can" (possible) over "may" (permissable).
Agree, but not for your reason. Although, before I looked it up, I would have.
Learning for a lifetime. :) http://www.oxforddictionaries.com/words/can-or-may
A question is being asked as to where the scarf can be bought. It's not asking for permission, so asking, "Where may I buy this scarf?" sounds either like asking for permission, not which store, or it sounds strangely formal and awkward.
Is Можна neuter in imperfective infinitive? That said, would Вміти be conjugated gender harmonious in the same tense(s)? Спасибo
It's more natural to say "a scarf," rather than "the scarf," unless a particular scarf is being discussed prior to asking the question in this exercise. Even then, a person is more like to say "that or this" scarf, not "the scarf."
I think "Where may I buy a scarf?" should be accepted. The mouse-over tips for "можна" give both "one can buy" and "one may buy" as hints. Sure, splitting hairs, one can argue that in English there is a distinction between permission and capability, but I think the de facto difference is merely in politeness level.