Question

25 if an atom has 19 protons and 20 neutrons, what is the atomic number? a 19 b 1 c 20 d 39

Explanation:

Step1: Recall atomic number definition

The atomic number of an atom is equal to the number of protons in its nucleus.

Step2: Identify number of protons

The atom has 19 protons.

Answer:

A. 19