The energy equivalent of 1 amu in MeV is

The correct answer is Option (3) → 931.5 MeV

By Einstein's mass-energy relation \( E = mc^{2} \), the energy equivalent of a mass of 1 u (1 amu), \( 1\,\mathrm{u} = 1.66\times10^{-27}\,\mathrm{kg} \), is found in joules and then converted to MeV.

    \( E = 1.66\times10^{-27}\,\mathrm{kg}\times(3\times10^{8}\,\mathrm{m\,s^{-1}})^{2} = 1.49\times10^{-10}\,\mathrm{J} \)

Using \( 1\,\mathrm{eV} = 1.6\times10^{-19}\,\mathrm{J} \):

    \( \displaystyle E = \frac{1.49\times10^{-10}}{1.6\times10^{-19}}\,\mathrm{eV} = 9.3\times10^{8}\,\mathrm{eV} \approx 931.5\,\mathrm{MeV} \)

The value from the rounded constants is about 930 MeV; with the more precise values \( c = 2.998\times10^{8}\,\mathrm{m\,s^{-1}} \) and \( 1\,\mathrm{u} = 1.6605\times10^{-27}\,\mathrm{kg} \) it is exactly 931.5 MeV, so \( 1\,\mathrm{u} = 931.5\,\mathrm{MeV}/c^{2} \).

NCERT (2026-27):
Nuclear Binding Energy – “… Example 13.3 Find the energy equivalent of one atomic mass unit, first in Joules and then in MeV. … To convert it into energy units, we multiply it by c² and find that energy equivalent

    \( \displaystyle = 0.9315 \times 10^{9}\ \mathrm{eV} = 931.5\ \mathrm{MeV} \quad \text{or,} \quad 1\,\mathrm{u} = 931.5\ \mathrm{MeV}/c^{2} \)”