The atomic number (Z) uniquely identifies a chemical element. In an uncharged atom, the atomic number is also equal to the number of electrons.
The atomic number, Z, should not be confused with the mass number, A, which is the number of nucleons, the total number of protons and neutrons in the nucleus of an atom.
In this video Kristine Born explains this two concepts in more detail.
<u>Answer:</u> The energy released in the given nuclear reaction is 1.3106 MeV.
<u>Explanation:</u>
For the given nuclear reaction:

We are given:
Mass of
= 39.963998 u
Mass of
= 39.962591 u
To calculate the mass defect, we use the equation:

Putting values in above equation, we get:

To calculate the energy released, we use the equation:

(Conversion factor:
)

Hence, the energy released in the given nuclear reaction is 1.3106 MeV.
Last option that is none of above is right answer.
Answer:
inside the nucleus of an atom are protons and electrons.