What value is closest to the mass of the atom? 4 amu 6 amu 10 amu 14 amu

The right answer is 10 amu.

The unit of unified atomic mass, of symbol "u", is a standard unit of measure, used to express the mass of atoms and molecules.

This unit does not belong to the International System (SI), and its value is obtained experimentally. It is defined as 1/12 of the mass of a nuclide 12C (carbon 12), unbound at rest and in its ground state. In other words, a 12C atom has a mass of exactly 12u, and a mole of 12C atoms (N atoms, where N is the number of Avogadro) has a mass of exactly 12g. As a result, 1 u is approximately 1.660 538 921 × 10-27 kg.

The average mass of a nucleon depends on the total number of nucleons in the atomic nucleus, because of the mass defect. This is why the mass of a proton or a neutron taken separately is strictly greater than 1 u.

In the nucleus, we can see that there are 10 nucleons (protons and neutrons) so the mass of the atom is close to 10amu.