Answer:
A standard dimension for sandwiches and rulers
It's in your hand though you cannot feel it. Only you and time can reveal it.
Without this, H2O would just be 2O
If you agree give me one of these.
Barren location, infertile and dry; my name means "to leave", it's not heard to see why
I touch the Earth, I touch the sky, but if I touch you, you’ll likely die. What am I?