Question

look at the text below. if there is an error with subject - verb agreement, select the incorrect verb and type it correctly. otherwise, submit the text without making any changes. the number of protons in an atom are expressed by that elements atomic number on the periodic table.

Explanation:

The subject "The number of protons" is singular, so the verb should be singular too. "Are" is incorrect and should be "is".

Answer:

The number of protons in an atom is expressed by that element's atomic number on the periodic table.