To identify the equation that represents a fission reaction, we need to understand what characterizes nuclear fission. Fission is the process in which a large nucleus splits into two or more smaller nuclei, along with a few neutrons and a large amount of energy.
Let's evaluate each of the given equations:
1. [tex]\(\mathrm{{ }_7^{14} N+{ }_1^1 H \longrightarrow{ }_8^{15} O}\)[/tex]
This equation represents a fusion reaction because two lighter nuclei (nitrogen-14 and hydrogen-1) combine to form a heavier nucleus (oxygen-15).
2. [tex]\(\mathrm{{ }_{92}^{235} U + { }_0^1 n \longrightarrow{ }_{55}^{140} Cs + { }_{37}^{94} Rb + 2{ }_0^1 n}\)[/tex]
In this reaction, a uranium-235 nucleus absorbs a neutron and splits into two smaller nuclei (cesium-140 and rubidium-94), releasing additional neutrons. This is a classic example of a fission reaction.
3. [tex]\(\mathrm{{ }_4^9 Be + { }_2^4 He \longrightarrow{ }_6^{12} C + { }_0^1 n}\)[/tex]
This equation represents a fusion reaction where beryllium-9 and helium-4 (alpha particle) combine to form carbon-12 and a neutron.
4. [tex]\(\mathrm{{ }_{93}^{239} Np \longrightarrow{ }_{94}^{239} Pu +{ }_{-1}^0 e}\)[/tex]
This equation represents a beta decay reaction where neptunium-239 decays into plutonium-239 while releasing a beta particle (an electron).
After examining all four equations, the one that represents a fission reaction is:
[tex]\[
\mathrm{{ }_{92}^{235} U + { }_0^1 n \longrightarrow{ }_{55}^{140} Cs + { }_{37}^{94} Rb + 2{ }_0^1 n}
\][/tex]
