Question

question 1
1 pts
which element has 9 protons?
beryllium
potassium
fluorine
question 2
1 pts
an atom has 19 protons and 20 neutrons. what is the mass?

Explanation:

Step1: Recall atomic number concept

The atomic number of an element is equal to the number of protons. Fluorine has an atomic number of 9, so it has 9 protons. Beryllium has 4 protons and potassium has 19 protons.

Step2: Calculate atomic mass

The mass number of an atom is the sum of the number of protons and neutrons. Given 19 protons and 20 neutrons, the mass number is $19 + 20=39$.

Answer:

Question 1: C. fluorine
Question 2: 39