Question

a neutron strikes a plutonium-239 nucleus, starting a fission reaction. the products are a strontium-96 nucleus, a barium-140 nucleus, and some neutrons. how many neutrons are in the products of the reaction? (1 point)
four
two
three
one

Explanation:

Step1: Calculate the total mass number on the reactant side

The mass number of plutonium - 239 is \(A_{Pu}=239\), and the mass number of the neutron is \(A_n = 1\). So the total mass number on the reactant side is \(A_{reactants}=239 + 1=240\)

Step2: Calculate the total mass number on the product side from the known nuclei

The mass number of strontium - 96 is \(A_{Sr}=96\), and the mass number of barium - 140 is \(A_{Ba}=140\). Let the number of neutrons be \(x\) and the mass number of a neutron is \(1\). So the total mass number on the product side is \(A_{products}=96 + 140+x\)

Step3: Set up the equation based on mass - number conservation

Since \(A_{reactants}=A_{products}\) (mass - number conservation in nuclear reactions), we have the equation \(240=96 + 140+x\)

Step4: Solve for \(x\)

Simplify the right - hand side of the equation: \(96+140+x=236 + x\). Then \(240=236+x\). Subtract 236 from both sides: \(x=240 - 236=4\)

Answer:

four