Mid-ocean ridges are underwater mountainous regions formed by the separation of

Oceanic plates. The ocean floor is made out of many oceanic plates, and when those diverge, or separate, they form mid-ocean ridges.

hydrogen is a compound or a single element and a element is a pure substence that cannot be separated into simpler subtances

clorine is a compound its a chemical substance that forms when two or more different elements combine

so both hydrogen and clorine are compounds