To determine which reaction is an example of gamma emission, let's analyze each reaction given in the problem. Gamma emission involves the release of gamma rays, which are high-energy photons, from the nucleus of an atom. This type of radiation does not change the atomic number or the atomic mass of the element.
1. [tex]${ }_5^{10} B+{ }_0^1 n \rightarrow{ }_3^7 Li +{ }_2^4 He$[/tex]
- This reaction shows a boron-10 nucleus capturing a neutron ([tex]${ }_0^1 n$[/tex]) and splitting into lithium-7 and helium-4. This is a form of nuclear reaction but does not involve gamma emission.
2. [tex]${ }_{96}^{242} Cm \rightarrow{ }_{94}^{238} Pu +{ }_2^4 He$[/tex]
- This reaction is an alpha decay where curium-242 decays into plutonium-238 and an alpha particle (helium-4 nucleus). This is characteristic of alpha decay, not gamma emission.
3. [tex]${ }_{21}^{46} Sc \rightarrow{ }_{21}^{46} Sc +$[/tex] energy
- In this reaction, scandium-46 remains scandium-46 but releases energy. The reaction indicates the nucleus is in an excited state and returns to its ground state by emitting energy. This emission is likely in the form of gamma rays, which is characteristic of gamma emission where the atomic number and mass number remain unchanged, only energy is released in the form of gamma rays.
4. [tex]${ }_{22}^{51} Ti \rightarrow{ }_{23}^{51} v +{ }_{-1}^0 \beta$[/tex]
- This reaction depicts a beta decay process, where titanium-51 decays into vanadium-51 and a beta particle (electron). This is characteristic of beta decay, not gamma emission.
5. [tex]${ }_{92}^{235} U +{ }_0^1 n \rightarrow{ }_{52}^{138} Te +{ }_{40}^{96} Zr +2{ }_0^1 n
- This reaction represents a fission process where uranium-235 absorbs a neutron and splits into tellurium-138, zirconium-96, and releases additional neutrons. This is a fission reaction, not gamma emission.
Based on the analysis of each reaction, the example of gamma emission is:
Option 3: $[/tex]{ }_{21}^{46} Sc \rightarrow{ }_{21}^{46} Sc +$ energy
In this reaction, the nuclear identity (both atomic number and mass number) of scandium-46 remains unchanged, and the nucleus releases energy in the form of gamma rays. The correct answer is option 3.
