A clinic needs the element supplied for supplemental respiratory support. A table lists oxygen with atomic number 8 and nitrogen with atomic number 7. Enter the proton count of one atom of the intended element.
Bonne réponse
8
Explication
The respiratory-support gas is oxygen, and its listed atomic number means each oxygen atom has 8 protons. Entering 7 would select nitrogen, which may be present in air but is not the element supplied for this purpose.