Answer:
[tex]^{139}_{56}Ba[/tex]
Explanation:
The fission reaction taking place given in the question is:
[tex]^{235}_{92}U+^{1}_{0}n\rightarrow ^{A}_{Z}Ba+^{94}_{36}Kr+3^{1}_{0}n[/tex]
The mass is conserved in the reaction.
So,
235 + 1 = A + 94 + 3×1
A = 139 g/mol
Also, number o protons remain same. So,
92 = Z + 36
Z = 56
The isotopic symbol is [tex]^{139}_{56}Ba[/tex]