Question

figure 1: converting hydrogen to helium
reactants(in):
4 protons
products(out):
he nucleus
2 gamma rays
2 positrons
2 neutrinos
total final mass is
0.7% lower. the
\lost\ mass has
been converted
into energy.
e=mc²
h = hydrogen
he = helium
proton (+)
neutron
neutrino
positron
during a star’s lifespan, interior heat and radiation is provided by nuclear reactions in the star’s
core. during the process of nuclear fusion, high temperatures and pressures are so intense in the
sun’s core that hydrogen nuclei combine with one another to form helium atoms. the \lost\ mass is
converted into energy e=mc² as illustrated in figure 1.
reference:
rosenvall, a (2021) created for usbe, creative commons license.
which energy conversion is taking place in the process shown in figure 1: converting hydrogen to helium?
① chemical energy is converted into electrical energy
② thermal energy is converted into nuclear energy
③ no energy conversions are taking place
④ nuclear energy is converted into electromagnetic and thermal energy

Explanation:

The process shown is nuclear fusion (hydrogen to helium in a star's core). The "lost" mass is converted to energy ($E = mc^2$), and the products include gamma rays (electromagnetic) and the process releases energy as heat (thermal). So nuclear energy (from mass - energy conversion) is converted to electromagnetic (gamma rays) and thermal energy. Let's analyze the options:

• Option 1: Chemical to electrical is incorrect (no chemical reaction here, it's nuclear fusion).
• Option 2: Thermal to nuclear is incorrect (nuclear fusion produces energy, not the other way).
• Option 3: No energy conversions is wrong as mass is converted to energy.
• Option 4: Nuclear energy (from mass - energy conversion in fusion) is converted to electromagnetic (gamma rays) and thermal energy (heat from the reaction) matches the process.

Answer:

D. Nuclear energy is converted into electromagnetic and thermal energy (assuming the last option is D, as per the description of the options where the correct one is about nuclear energy converting to electromagnetic and thermal; if the option numbering is different, adjust the identifier but the text should be "Nuclear energy is converted into electromagnetic and thermal energy").