Probability — Maths STD 11 Science — Question

The experiment will continue until we get a head.
So, head may come up on the first toss and the outcome will be H,
If first toss is tail and 2nd toss is head outcome will be TH,
In the same way, if first and second toss is tails and third toss is a head, outcome will be TTH and so on till head is obtained.
Hence, the desired sample space is S= {H, TH, TTH, TTTH, TTTTH,...}