* Group 2 elements: These are the alkaline earth metals (Be, Mg, Ca, Sr, Ba, Ra).

* Bromine: Bromine (Br) has 35 protons (its atomic number is 35).

* Sulfur: Sulfur (S) has 16 protons (its atomic number is 16).

We need a group 2 element with:

* Fewer protons than bromine (35): This eliminates strontium (Sr), barium (Ba), and radium (Ra), which all have more protons than bromine.

* More protons than sulfur (16): This eliminates beryllium (Be) which has only 4 protons.

The answer: The only group 2 element that fits both conditions is Magnesium (Mg). Magnesium has 12 protons.