Answer:
[tex]\\ N=n * N_{A}[/tex]
We do not have [tex]n[/tex] - the amount of substance.
[tex]n=\frac{m}{M}\\[/tex]
The molecular weight ([tex]M[/tex]) of Bromine is 80.
[tex]n=\frac{4}{80} = 0.05 \text{ mol}[/tex]
[tex]N = 0.05 * 6.02 * 10^{23} = 0.301 * 10^{23}[/tex]
