Explanation:
We have to find the number of neutrons that are present in Bromine-80. If we look for it in the periodic table we will find that the atomic number of Bromine is 35. The mass number is the one that we are given: 80.
By definition the atomic number is equal to the number of protons and the mass number is equal to the number of protons plus the number of neutrons.
mass number = n° of protons + n° of neutrons
atomic number = n° of protons
We can replace the values that we have in the equations to find the n° of neutrons present in bromine-80.
atomic number = n° of protons = 35
n° of protons = 35
mass number = n° of protons + n° of neutrons
n° of neutrons = mass number - n° of protons
n° of neutrons = 80 - 35
n° of neutrons = 45
Answer: 45
