If you were to flip a coin twenty times, approximately how many times do you think heads would come up?

Theoretically 10 because the 50/50 chance realistically though you'll get more or less

The probability of heads on any toss is just as likely as the probability of tails because each coin toss is an independent event.  In other words two events related in such a way that knowing about the occurrence of one event has no effect on the probability of the other event, in others words independent.

It does not matter if you have flipped a coin 5 times and it was heads, it is not "due" to come up tails.  This is an incorrect assumption just like it is incorrect to believe you are "on a roll" because 5 times it was heads.  

Ais the correct answer