Given below are two statements: 
In light of the above statements, choose the correct answer from the options given below:
Given below are two statements: 
The center of a disk of radius $ r $ and mass $ m $ is attached to a spring of spring constant $ k $, inside a ring of radius $ R>r $ as shown in the figure. The other end of the spring is attached on the periphery of the ring. Both the ring and the disk are in the same vertical plane. The disk can only roll along the inside periphery of the ring, without slipping. The spring can only be stretched or compressed along the periphery of the ring, following Hooke’s law. In equilibrium, the disk is at the bottom of the ring. Assuming small displacement of the disc, the time period of oscillation of center of mass of the disk is written as $ T = \frac{2\pi}{\omega} $. The correct expression for $ \omega $ is ( $ g $ is the acceleration due to gravity): 
Let $ a_0, a_1, ..., a_{23} $ be real numbers such that $$ \left(1 + \frac{2}{5}x \right)^{23} = \sum_{i=0}^{23} a_i x^i $$ for every real number $ x $. Let $ a_r $ be the largest among the numbers $ a_j $ for $ 0 \leq j \leq 23 $. Then the value of $ r $ is ________.
Quantum mechanics is an evolving and much-advanced field of science that aims at understanding the properties of matter and objects in relation to their corresponding atomic and sub-atomic nature. It further illustrates the characteristics of the atoms, protons, electrons, and neutrons specifically and in the context of each other. It aims at studying electromagnetic radiation as well. This is a sub-part of the wider theory of quantum physics.
Read Also: Quantum Mechanical Model of Atom
Presently, the scientific world has only two acceptable and working models of quantum mechanics. Such as,
The basis of this model of the Bohr is seen in terms of mathematics which is used for understanding the complex structures.
This quantum theory ultimately defines the exact properties of matter over a period of time. It usually works on the uncertainty principle.