Answer:
31
Step-by-step explanation:
To calculate the atomic mass of phosphorus (P), you need to consider the sum of protons and neutrons in the nucleus of a phosphorus atom.
Given that phosphorus has 15 protons and 16 neutrons, you can add these numbers together to find the total number of particles in the nucleus:
Atomic mass = Number of protons + Number of neutrons
Atomic mass = 15 protons + 16 neutrons
Atomic mass = 31
Therefore, the atomic mass of phosphorus is 31 atomic mass units (amu).