Answer:
I think its the first one. unless there is more to the question
An atomic mass unit is defined as a mass equal to one twelfth the mass of an atom of carbon-12. The mass of any isotope of any element is expressed in relation to the carbon-12 standard. For example, one atom of helium-4 has a mass of 4.0026 amu. An atom of sulfur-32 has a mass of 31.972 amu.
12.2 C
It has 3 significant figures now.
Anthony’s because it explains way more
