6
12
18
Zero
Answer is Right!
Answer is Wrong!
The correct answer is A. 6.
The atomic number of an element is the number of protons in the nucleus of an atom of that element. The atomic mass of an element is the average mass of one atom of that element, expressed in atomic mass units (amu).
Carbon has an atomic number of 6 and an atomic mass of 12. This means that a carbon atom has 6 protons in its nucleus and an average mass of 12 amu.
Option B is incorrect because 12 is the atomic mass of carbon, not the number of protons in the nucleus of a carbon atom.
Option C is incorrect because 18 is not a valid atomic number for any element.
Option D is incorrect because carbon atoms have 6 protons in their nucleus, not 0.