# Question 5d492

May 25, 2017

$5$ protons, $6$ neutrons

#### Explanation:

All atoms of boron always contain $5$ protons, as that defines its atomic number ($5$).

The mass number for boron-11 is $11$ (it's given to you), and recall that the number of protons plus the number of neutrons equals the mass number.

A "^11B# atom thus contains

$11 \text{(mass number") - 5 "(protons)} = \textcolor{red}{6}$ neutrons