Question

an atom has 20 electrons and 20 neutrons. assume it has a net charge of zero. what is the total mass of this atom? multiple choice 40 80 20 10

Explanation:

Step1: Determine number of protons

Since the atom has a net - charge of zero and 20 electrons, the number of protons is equal to the number of electrons. So, the number of protons $p = 20$.

Step2: Calculate atomic mass

The atomic mass $A$ of an atom is the sum of the number of protons and neutrons. Given $p = 20$ and number of neutrons $n=20$, then $A=p + n$. Substituting the values, we get $A=20 + 20=40$.

Answer:

40