Question

Identify the location where the whole mass of the atom was found.
A. Equally dispersed throughout the entire atom cloud
B. Equally divided between all its parts: the electrons, neurons, protons
C. Concentrated in the orbital cloud
D. Concentrated in the nucleus
E. Determined by spectroscopic analysis

Answer 1

The atomic nucleus was first discovered by Rutherford in 1906. He studied the scattering of a $\alpha$-particle from a thin gold foil in order to investigate the structure of an atom. Rutherford proposed that an atom has a tiny positively charged core called the nucleus which contains most of the mass $99.9\%$ of the atom.

Complete answer:
The detailed outcomes of Rutherford’s model of atoms are given below;
-Most of the mass and all the positive charge of an atom is concentrated in a tiny core placed in the centre of the atom.
-The radius of the nucleus is of the order of ${10^{ - 15}}m$ and that of the atom is of the order of ${10^{ - 10}}m$. Therefore, the nucleus occupies only an extremely small portion of the size of the atom.
-The electrons occupy the space outside the nucleus. The negative charge on electrons and positive charge on protons present in the nucleus of the atom are equal in magnitude.Therefore, the net charge over an atom is equal to zero.
-Electrons revolve around the nucleus in various circular orbits similar to the way as planets orbit the sun in the solar system.

Hence, the correct option is (D).

Note: A nucleus has its own structure and consists of protons and neutrons.A proton is a positively charged particle and has a charge equal to that of an electron. However, the mass of a proton is about $1836$ times that of the electron.
Charge on proton, $e = + 1.6 \times {10^{ - 19}}C$.
Mass of proton, ${m_p} = 1.6726 \times {10^{ - 27}}kg$
A neutron is an electrically neutral particle and has mass almost around the mass of a proton.
Charge on neutron$= 0$
Mass of neutron, ${m_n} = 1.6750 \times {10^{ - 27}}kg$