Answer: the atomic mass number of 12 protons, 11
neutrons and 13 electrons is 23
Step-by-step explanation:
The atomic mass of an atom is the sum of protons and neutrons in an atom and is given by the symbol A.
The mass number is also called the nucleon number.
Atomic mass = No.of protons + No. of Neutrons
A=11+12
A=23