If a person is learning in a room where there is an active minyan, is he exempt from saying amen by kaddish, saying kedusha, standing when a torah is removed or returned to ark?
The situation is in a shul with a balcony/ezras nashim where you can hear the baal tefilah. The balcony is used for social distancing during the magefah and some chaburahs are active in balcony.
Regarding answering amen, kaddish, kedusha etc. it depends on your situation. If it evident that you are not davening together with the minyan then you don’t have to answer, however if it isn’t clear that you are not part of the minyan then you should answer.
Regarding standing for the sefer torah when it is being moved, the reason we do this is because of kavod for the sefer torah, which has nothing to do with being part of the minyan. Even when there is no minyan going on and a sefer torah is taken or returned to the ark we stand until the sefer torah leaves the room of is placed in it’s place. If you don’t see the sefer torah being moved, you don’t have to stand up. Additionally, if someone is learning and he doesn’t notice that the sefer torah is being moved, he doesn’t have to be informed since he didn’t he the sefer torah moving, he is not obligated to stand up.
Halichos Shlomo (Tefillah) 6-12, 12 ftnt. 37, Rambam Hilchos Sefer Torah 10-10, Y:D 292-2.