Number of neutrons can be calculated as = mass number-atomic number
so for all these elements, no. of neutrons will be calculated as:
For tin(Sn),
number of neutrons= 119-50
=69
For antimony(Sb),
No. of neutrons=122-51
=71
For Tellurium(Te),
No. of neutrons=128-52
=76
For iodine(I),
No. of neutrons= 127-53
= 74
So tellurium will have highest number of neutrons
