Number of neutrons of the elements can be calculated if the atomic number and mass number is known.
As, Number of neutrons= Mass number- Atomic number
For Tin(sn), the mass number is 119 and atomic number is 50, then
Number of neutrons= 119-50=69
For Antimony(sb), the mass number is 122 and the atomic number is 51, then
Number of neutrons=122-51=71
For Tellurium(te), the mass number is 128 and atomic number is 52,then
Number of neutrons=128-52=76
Fro Iodine(I), the mass number is 127 and the atomic number is 53, then
Number of neutrons=127-53=74
Since, the number of neutrons are large in Tellurium, therefore Tellurium have the greatest average number of neutrons.
