Please help!!!
After the fission of U-235 takes place, how many neutrons does the missing nucleus have?
A) 84
B) 85
C) 141
D) 143

The atomic number is consider a unique atom and element identifier. Describe the associated subatomic particle, and how it can be used to identify the atom.
A) The number of electrons changes in a unique way as the charge on the atom changes.
B) The proton number remains constant through changing the atomic charge, energy, and isotopes.
C) As the atom absorbs photons the way the photons interact in the nucleus gives the atomic number.
D) All isotopes of the an element have the same number of neutrons allowing it to describe the unique atom.

1. Considering the nuclear fission of uranium-235, it is known that its nucleus absorbs a slow-moving neutron, turning out into a nucleus of Kripton-92, a nucleus of Barium-141 and three extra neutrons.

Next, considering the following statements:

- U's atomic number is 92, therefore it contains 92 protons

- Kr's atomic number is 36, therefore it contains 36 protons

- Ba's atomic number is 56, therefore it contains 56 protons

In such a way, we can compute the number of neutrons in the nucleus of Ba, as we know that the total number of neutrons are always conserved. Thus:

- On the left side of the reaction: (235-92) neutrons of the uranium + 1 neutron absorbed = 144 neutrons

- On the right side of the reaction: (92-36) neutrons of the krypton + X neutrons of the barium + 3 neutrons = 144

Therefore:

[tex]56+x+3=144\\x=144-56-3=85[/tex]

Thus, the nucleus of barium has 85 neutrons.

2. In this case, the correct answer is B) The proton number remains constant through changing atomic charge, energy, and isotopes. We must consider that the atomic number is understood as the number of protons in the nucleus of the considered element. It would change just if the element undergoes a nuclear process.

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