Question

balance the nuclear fission reaction 2 neutrons 3 neutrons 6 neutrons 4 neutrons

Explanation:

Step1: Calculate the total mass number on the left - hand side

The mass number of \(_{92}^{235}U\) is \(235\), and the mass number of \(_{0}^{1}n\) is \(1\). So the total mass number on the left - hand side is \(235 + 1=236\).

Step2: Calculate the total mass number on the right - hand side from the known nuclei

The mass number of \(_{56}^{139}Ba\) is \(139\), and the mass number of \(_{36}^{90}Kr\) is \(90\). The sum of their mass numbers is \(139+90 = 229\).

Step3: Determine the number of neutrons

Let the number of neutrons be \(x\). Since mass number is conserved in a nuclear reaction (\(236=229 + x\)), then \(x=236 - 229=3\).

Answer:

3 neutrons