Question

An explosion of atomic bomb releases an energy of `7.6xx10^(13)J`. If `200 MeV` energy is released on fission of one `.^(235)U` atom calculate (i) the number of uranium atoms undergoing fission. (ii) the mass of uranium used in the atom bomb

Answer 1

`E=7.6xx10^(13)J` , Energy released per fission`=200 MeV`
`=200xx10^(6)xx1.6xx10^(-19)=3.2xx10^(-11)J`
`"Number of uranium atoms"(n)=("Total energy")/("Energy per fission")`
`n=(7.6xx10^(13))/(3.2xx10^(-11))=2.375xx10^(24)"atoms"`
Avagadro number `(N)=6.023xx10^(23)"atoms"`
Mass of uranium `=`
`(nxx235)/(N)=(2.375xx10^(24)xx235)/(6.023xx10^(23))=92.66g`