Read the following passage and answer the questions.
Nuclear power stations and the sun both draw their energy from atomic nuclei. In a reactor, a neutron strikes a nucleus of uranium-235. The nucleus splits into two nuclei and a few neutrons. About 200 MeV of energy is released each time a uranium nucleus splits in this way. A reactor uses this energy to produce electricity. The sun works in a different way. In its core, very light nuclei, such as those of hydrogen, join to form heavier nuclei. These nuclei are positively charged and repel each other. So the joining takes place only at a very high temperature, where the nuclei move fast enough to come very close. Scientists are also trying to make light nuclei join in a controlled way on the earth.
The mass converted into energy when one uranium nucleus splits is about (1 u = 931.5 MeV/\(c^{2}\))
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 0.215 u
Mass and energy are related by \( E=mc^{2} \). Since 1 u of mass is equivalent to 931.5 MeV, the mass converted is the energy released divided by 931.5 MeV per u.
Given:
\( E=200\ \mathrm{MeV} \)
\( 1\ \mathrm{u}=931.5\ \mathrm{MeV}/c^{2} \)
\( \begin{aligned} \Delta m &= \frac{E}{c^{2}} \\ &= \frac{200}{931.5}\ \mathrm{u} \\ &\approx 0.215\ \mathrm{u} \end{aligned} \)
Therefore, about 0.215 u of mass is converted into energy each time a uranium nucleus splits.
NCERT (2026-27):
Mass – Energy – “Einstein gave the famous mass-energy equivalence relation”
\( E=mc^{2} \)\( \qquad (13.6) \)
Example 13.3 – “… = 0.9315 × 109 eV = 931.5 MeV or, 1u = 931.5 MeV/c2”