Question

which equation represents a fission reaction?

$$ _ { 92 } ^ { 235 } mathrm { u } + _ { 0 } ^ { 1 } mathrm { n } ightarrow _ { 55 } ^ { 140 } mathrm { cs } + _ { 37 } ^ { 94 } mathrm { rb } + 2 _ { 0 } ^ { 1 } mathrm { n } $$

$$ _ { 4 } ^ { 9 } mathrm { be } + _ { 2 } ^ { 4 } mathrm { he } ightarrow _ { 6 } ^ { 12 } mathrm { c } + _ { 0 } ^ { 1 } mathrm { n } $$

$$ _ { 7 } ^ { 14 } mathrm { n } + _ { 1 } ^ { 1 } mathrm { h } ightarrow _ { 8 } ^ { 15 } mathrm { o } $$

$$ _ { 93 } ^ { 239 } mathrm { np } ightarrow _ { 94 } ^ { 239 } mathrm { pu } + _ { - 1 } ^ { 0 } mathrm { n } $$

Explanation:

Nuclear fission is a process where a heavy nucleus splits into smaller nuclei. In the first equation, \(_{92}^{235}\text{U}\) (a heavy uranium nucleus) absorbs a neutron (\(_{0}^{1}\text{n}\)) and splits into \(_{55}^{140}\text{Cs}\) (cesium) and \(_{37}^{94}\text{Rb}\) (rubidium) along with more neutrons. This is characteristic of fission. The second equation (\(_{4}^{9}\text{Be}+_{2}^{4}\text{He}\to_{6}^{12}\text{C}+_{0}^{1}\text{n}\)) is a fusion - like process (combining lighter nuclei). The third equation (\(_{7}^{14}\text{N}+_{1}^{1}\text{H}\to_{8}^{15}\text{O}\)) is a nuclear transmutation (not fission). The fourth equation (\(_{93}^{239}\text{Np}\to_{94}^{239}\text{Pu}+_{-1}^{0}\text{n}\)) is a beta - decay (not fission).

Answer:

\(_{92}^{235}\text{U}+_{0}^{1}\text{n}\to_{55}^{140}\text{Cs}+_{37}^{94}\text{Rb}+2_{0}^{1}\text{n}\)