If a coin is flipped 10 times, what percentage will start with heads If a coin is tossed 10x, out of all the possibilities, what percentage will start with heads?
Assuming you ignore the "land on its edge" cases, the answer is 50%.
If you mean heads plural then I would say $25$% cuz you have to get the first $2$ heads and that is $1/4$ chance.  The other $8$ don't really matter.