Final answer:
One mole of carbon has a mass of 12.0 g and the number of carbon nuclei in a kilogram is 5.02×10^25.
Step-by-step explanation:
The mass of a single carbon atom is commonly expressed in atomic mass units (amu) or unified atomic mass units (u). The atomic mass unit is a unit of mass used to express atomic and molecular weights. The standard reference for atomic masses is based on the carbon-12 isotope.
The atomic mass of a carbon-12 atom is defined as exactly 12 atomic mass units. This means that a single carbon-12 atom has a mass of 12 u. Keep in mind that this is the standard for atomic masses, and it is used as a reference point for expressing the masses of other atoms.
One mole of carbon has a mass of 12.0 g, since it is nearly pure ¹2C. Thus, the number of carbon nuclei in a kilogram is 5.02×10^25.