boron has an atomic mass of 11 and atomic number of 5 so the number of neutrons must be

Answer 1

Boron having an atomic number of 5 means that it will have 5 protons.

5 protons = 5 atomic mass units

11 atomic mass units in total.

Neutrons also have a atomic mass unit of 1.

5 + 6 = 11

So there are 6 neutrons.