Waht is subscripted text?

Answer 1

You have seen in mathematics when using logarithmic. In Log(x) with base 2, 2 is written quite below the log and x. It is because 2 is subscripted to represent base of log.
Similarly the superscript is when you see something in its power. eg. 2^3. 3 is superscripted here.

Answer 2

The '₂' in Carbon dioxide (CO₂) is subscripted.

Answer 3

tq now I understand clearly