A file containing C source code. If I rename the file to something else without the .c file extension and try to type the file command with the new file extension(i.e the name of the file having C source code hello.c and the new file hello.txt).What output the file command will show for hello.txt?

If I change the group membership of the .plan and .project files to my alternate groups using the chgrp command. ie: chgrp whales .plan .project

in that case can my partner(who belongs to the different group) use finger command to see my .project and .plan files? If yes explain the reason.