Respuesta :

Answer:

The answer to your question is: 20

Explanation:

Atomic number is the number of proton and atom has. Each element has a specific number of protons, if the number of protons change, then this is a new element.

Mass number is the number of protons and neutrons and atom has.

                       Mass number = protons + neutrons

Data

Number of protons = ?

Atomic number = 20

Then,

           atomic number = number of protons = 20