The red arrow is pointed at different locations of an atom of nitrogen. where is it pointing to the greatest concentration of atomic mass?

The arrow is pointed to the greatest concentration of atomic mass in A.

The atom is made up of subatomic particles. The basic subatomic particles are;

The electron is found on the shells outside the nucleus while the protons and neutrons are found inside the nucleus.

The greatest concentration of atomic mass is found in the nucleus indicated in figure A where the neutrons and protons are located.

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option A = In first diagram red arrow pointed towards the greatest concentration of atomic mass.

Explanation:

Every atom consist of nucleus or a positive center. The protons and neutrons are present with in the nucleus while electrons are present out side the nucleus. All these three subatomic particles construct an atom. The number of protons or number of electrons are the atomic number of an atom while the number of protons and number of neutrons are the mass number of an atom. A neutral atom have equal number of protons and electrons. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other.

Nitrogen consist of seven protons and seven neutrons present with in nucleus and seven electrons are present out side the nucleus.

Electron:

The electron is subatomic particle that revolve around outside the nucleus and has negligible mass. It has a negative charge.

Symbol= e-

Mass= 9.10938356×10-31 Kg

It was discovered by j. j. Thomson in 1897 during the study of cathode ray properties.

Neutron and proton:

The neutron and proton are present inside the nucleus. Proton has positive charge while neutron is electrically neutral. Proton is discovered by Rutherford while neutron is discovered by James Chadwick in 1932.

Symbol of proton= P+  

Symbol of neutron= n0  

Mass of proton=1.672623×10-27 Kg

Mass of neutron=1.674929×10-27 Kg