On an average how many neutrons are emitted in the fission reaction of U-235?
U-235 after absorbing a neutron becomes U-236 and then this “Unstable” isotope fission to give daughter products and in the process neutrons are emitted.
Interesting finding is that every time a U-236 fissions same daughters are not formed. The pair of daughters formed is different in each fission tough few pairs are highly probable.
We can give you some examples: 23692U→13753I+9739Y+2n23692U→14056Ba+9436Kr+2n
Here in these examples we have two neutrons there might be such fragments formed that 3 neutrons are emitted.
Average no.of neutrons=Total no. of neutrons foundTotal no. of fission events
This is an experimental work and the number comes to be almost 2.4.
Remember these neutrons trigger the next fission reaction and we get a "Self - Sustaining Chain Reaction".