Which statement best explains why hydrogen's atomic number is equal to its mass?

Question

A. Hydrogen is in the first row and the first column of the periodic table
B. Hydrogen does not have any neutrons
C. Hydrogen is stable, with two electrons in its outer shell
D. Hydrogen only has one electron

Answer 1

The statement that best explains why hydrogen's atomic number is equal to its mass is:

B. Hydrogen does not have any neutrons.

Hydrogen has an atomic number of 1, which means it has 1 proton. The most common isotope of hydrogen (protium) has no neutrons, giving it an atomic mass of approximately 1. Since the atomic mass is essentially the sum of protons and neutrons, with hydrogen having only one proton and no neutrons, its atomic number is equal to its mass.