Answer:
in the nucleus
Explanation:
The majority of mass of an atom consists in the nucleus which consists of protons and neutrons. The mass of a proton is 1.6726219 × 10⁻²⁷ kilograms and the mass of neutron is 1.674929 x 10⁻²⁷ kg while the mass of an electron is 9.109390 x 10⁻³¹ kg.
As it can be seen that the masses of both the protons and neutrons are higher than that of an electron the most mass lies in the nucleus.
