Radiocarbon (¹⁴C) is produced in the atmosphere as a result of:

Question

The ratio of the mass densities of nuclei of $ ^{40}\text{Ca} $ and $ ^{16}\text{O} $ is close to:

Answer 1

We match each option against the actual nuclear reaction responsible for making carbon-14 in the atmosphere.

Solar radiation acting on carbon dioxide is not correct, carbon dioxide is a later product in the cycle, formed once carbon-14 already exists and combines with oxygen, it is not the starting material struck by radiation.
Ultraviolet light acting on atmospheric oxygen is actually the process that forms ozone in the stratosphere, it has no role in producing carbon-14.
Lightning discharge in the atmosphere can create some nitrogen oxides, but it is not the nuclear process that forms carbon-14.
Cosmic rays generate fast neutrons in the upper atmosphere, and these neutrons strike nitrogen-14 nuclei, converting them into carbon-14 through the reaction $^{14}_{7}N + n \to \,^{14}_{6}C + p$, this is the well documented mechanism behind radiocarbon dating.

So option B is correct.

Answer 2

We match each option against the actual nuclear reaction responsible for making carbon-14 in the atmosphere.

Solar radiation acting on carbon dioxide is not correct, carbon dioxide is a later product in the cycle, formed once carbon-14 already exists and combines with oxygen, it is not the starting material struck by radiation.
Ultraviolet light acting on atmospheric oxygen is actually the process that forms ozone in the stratosphere, it has no role in producing carbon-14.
Lightning discharge in the atmosphere can create some nitrogen oxides, but it is not the nuclear process that forms carbon-14.
Cosmic rays generate fast neutrons in the upper atmosphere, and these neutrons strike nitrogen-14 nuclei, converting them into carbon-14 through the reaction $^{14}_{7}N + n \to \,^{14}_{6}C + p$, this is the well documented mechanism behind radiocarbon dating.

So option B is correct.

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