Question

the number of protons in an element is also called its?
valence number
atomic number
atomic mass
isotope number
clear my selection

Explanation:

The atomic number of an element is defined as the number of protons in the nucleus of its atom. Valence number relates to the combining capacity, atomic mass is the sum of protons and neutrons, and isotope number is related to different forms of an element with the same number of protons but different neutrons.

Answer:

B. atomic number