The energy equivalent of 5 g of substance is

The correct answer is Option (1) → \( 2.8\times10^{33}\,\mathrm{eV} \)

By Einstein's mass-energy relation a mass m is equivalent to the energy \( E = mc^{2} \).

    \( m = 5\,\mathrm{g} = 5\times10^{-3}\,\mathrm{kg} \)

    \( E = (5\times10^{-3})(3\times10^{8})^{2}\,\mathrm{J} = 4.5\times10^{14}\,\mathrm{J} \)

Converting joule to electron volt with \( 1\,\mathrm{eV} = 1.6\times10^{-19}\,\mathrm{J} \):

    \( \displaystyle E = \frac{4.5\times10^{14}}{1.6\times10^{-19}}\,\mathrm{eV} \approx 2.8\times10^{33}\,\mathrm{eV} \)

Note: NTA picked this question from an NCERT (2026-27) example and changed the figures. Do not ignore NCERT while practising numericals.

NCERT (2026-27):
Mass – Energy – …