What is most likely true of an atom with a mass of 15 amu?

The total number of protons and neutrons is 15, most likely true of an atom with a mass of 15 amu.

Explanation:

The Atomic Mass of an atom is defined with its unit amu (atomic mass unit). Here, the atomic mass is given as 15 amu. We all know that,

       Atomic mass= Number of (Protons + Neutrons)  

The number of protons and electrons are equal in an atom of an element. Besides, For ex, if we follow, the atomic mass chart of elements, we can see that Nitrogen has the atomic mass number 15 amu.

They are having 7 protons, 7 electrons and 8 (more than 7) neutrons in the atom. Hence, we can easily justify the answer with the option (D).

i'm wiling to try and you : )

i believe the answer is three water molecules