Final answer:
In a bromine atom, a total of 17 electrons have the quantum number l=1, which are found in the fully occupied 2p and 3p subshells, and the partially occupied 4p subshell.
Step-by-step explanation:
The student has asked how many electrons in a bromine atom have the quantum number l=1. This quantum number represents the angular momentum of an electron in an atom and corresponds to the p orbitals. In the case of bromine, which has an atomic number of 35, the electron configuration can be represented as [Ar] 4s23d104p5. This means that the n=2 and n=3 shells, which include 2p and 3p subshells, are fully occupied, each with a set of six electrons (three p orbitals with two electrons each), and the 4p subshell has five electrons distributed among the three p orbitals. Therefore, in total, 6 (from 2p) + 6 (from 3p) + 5 (from 4p) = 17 electrons in a bromine atom have the quantum number l=1.