Question

Who proposed the planetary model of the atom?
A) Earnest Rutherford
B) Max Planck
C) Neils Bohr
D) James Chadwick
E) JJ. Thompson

Answer 1

Hint: In the planetary model of the atom the electrons will orbit around the nucleus like the planets orbit around the sun. Many atomic models have been proposed. We have to find which is similar to planetary motion.

Complete step by step answer:
The Bohr model of the atom proposed by Neils Bohr is similar to the planetary motion. Hence this model is also known as the planetary model of the atom. He describes that the negatively charged electrons will orbit around the positively charged nucleus. Similar to the gravitational force of attraction between the sun and the planets, in the Bohr model he describes a coulomb force of attraction between the electrons and nucleus.
The electrons orbits or shells can hold a certain number of electrons only. The orbits are named as Principal quantum number $n$. The energy levels having principal quantum number $n = 1,2,3,4....$ are assigned to the shells named $K,L,M,N.....$ respectively. The size of the atom increases as the number of electrons increases and the number of orbits also. The electron in the outermost orbit experiences less coulomb force of attraction. The energy of the orbit near the nucleus will be the least. The outermost orbit will possess the highest energy.
When the electron is transited from a higher energy state to a lower energy state then the electromagnetic radiation released will have a frequency equal to the energy difference of the initial and final states.

The answer is option C.

Note:
The Bohr model of the atom or planetary model of the atom was proposed by Neils Bohr by modifying the Rutherford model of the atom. In the Rutherford model, the nuclear model of the atom is only described. Neils Bohr fixed the electrons in orbits.