Question

Atoms consists of protons, neutrons and electrons. if the mass of neutrons and electrons were made half and two times respectively to their actual masses, then the atomic mass of c12

Answer 1

we know that mass of proton = mass of neutron = unified mass(u)

unified mass = 1.67 × 10⁻²⁷ kg = 1u

we know that mass of C - 12 = 12u = 6 protons + 6 neutrons

given that the mass of neutrons is halfed

⇒ mass of 6 neutrons = 6/2 neutrons = 3u

now the new mass of the C - 12 is 6u + 3u = 9u

⇒ the new mass of the C - 12 is 9

• even if electrons mass is doubled the mass does not become a considerable mass. so electrons mass is neglected
• the mass of 12 electrons even after doubling is 0.00653u. it is so small that it is neglected.