Question

which equation represents a fission reaction?
\\( \ce{^{14}_{7}n + ^{1}_{1}h -> ^{15}_{8}o} \\)
\\( \ce{^{235}_{92}u + ^{1}_{0}n -> ^{140}_{55}cs + ^{94}_{37}rb + 2^{1}_{0}n} \\)
\\( \ce{^{9}_{4}be + ^{4}_{2}he -> ^{12}_{6}c + ^{1}_{0}n} \\)
\\( \ce{^{239}_{93}np -> ^{239}_{94}pu + ^{0}_{-1}e} \\)

Explanation:

To determine which equation represents a fission reaction, we recall that nuclear fission is the splitting of a heavy nucleus into smaller nuclei, often accompanied by the release of neutrons.

• The first reaction (\(_{7}^{14}\text{N} + _{1}^{1}\text{H}

ightarrow _{8}^{15}\text{O}\)) is a nuclear fusion - like or transmutation reaction (a light nucleus is added to another nucleus), not fission.

• The second reaction (\(_{92}^{235}\text{U}+_{0}^{1}\text{n}

ightarrow_{55}^{140}\text{Cs}+_{37}^{94}\text{Rb}+2_{0}^{1}\text{n}\)) shows the heavy uranium - 235 nucleus splitting into two smaller nuclei (cesium - 140 and rubidium - 94) and releasing neutrons, which is characteristic of nuclear fission.

• The third reaction (\(_{4}^{9}\text{Be}+_{2}^{4}\text{He}

ightarrow_{6}^{12}\text{C}+_{0}^{1}\text{n}\)) is a nuclear reaction where two nuclei combine (a form of nuclear reaction but not fission; it is similar to a fusion - like reaction or a transmutation), not fission.

• The fourth reaction (\(_{93}^{239}\text{Np}

ightarrow_{94}^{239}\text{Pu}+_{- 1}^{0}\text{e}\)) is a beta - decay (a type of radioactive decay where a neutron in the nucleus turns into a proton and an electron is emitted), not fission.

Answer:

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