If you lost the ability to feel pain or to sense what you touched where might an injury have occurred or disease be located?

a

explanation:

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.

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