in my recent post with the photo of the Baby Ruth advertisement on the door window, i had the chemical formula for dextrose typed out like C6H12O6 and i thought there may come a time when you wished to type something in that format, like H2O for instance, so here is the html script. you’ll notice the characters that are smaller and drop downward are placed within the html subscript brackets.
C<sub>6</sub>H<sub>12</sub>O<sub>6</sub>
enjoy !