What is the justification of two strong peaks in the mass spectrum for bromine while for iodine only one peak at 127amu is indicated?

Answer 1

The mass spectrum of bromine shows two strong peaks because bromine has two naturally occurring isotopes - bromine-79 and bromine-81 - which have different masses. In contrast, iodine only has one naturally occurring isotope, iodine-127, which results in a single peak at 127 amu in its mass spectrum.