Question

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

• A. Action of solar radiations on CO₂ in the atmosphere
• B. Collision between fast neutrons and nitrogen nuclei in the atmosphere
• C. Action of ultraviolet light on atmospheric oxygen
• D. Lightning discharge in the atmosphere

Hint:

Recall the nuclear reaction used in radiocarbon dating, it starts with cosmic-ray produced neutrons striking nitrogen atoms.

Answer 1

The Correct Option is B

Step 1: Recall what radiocarbon is.
Radiocarbon, carbon-14, is a radioactive isotope of carbon formed continuously high in the atmosphere, and it is the basis of radiocarbon dating.
Step 2: Trace the source of neutrons.
Cosmic rays entering the atmosphere from space produce fast moving neutrons when they strike air molecules.
Step 3: Identify the nuclear reaction.
These fast neutrons collide with nitrogen-14 nuclei, the most abundant nitrogen isotope in air, converting nitrogen-14 into carbon-14 and releasing a proton, written as \(^{14}_{7}\mathrm{N} + n \to \,^{14}_{6}\mathrm{C} + p\).
Step 4: Rule out other options.
Solar radiation acting on carbon dioxide is not the actual mechanism, carbon dioxide is formed later when carbon-14 combines with oxygen. Ultraviolet light on atmospheric oxygen describes ozone formation, not carbon-14 production. Lightning discharge produces nitrogen oxides, not carbon-14.
Final Answer: B) Collision between fast neutrons and nitrogen nuclei in the atmosphere.