Assertion $(A)$ : The magnetic moment $(\mu)$ of an electron revolving around the nucleus decreases with increasing principle quantum number $(n)$.

Reason $(R)$ : Magnetic moment of the revolving electron, $\mu \propto n$.

Choose the correct alternative from the clues given at the end of the each statement:

$(a)$ The size of the atom in Thomson’s model is ………. the atomic size in Rutherford’s model. (much greater than/no different from/much less than.)

$(b)$ In the ground state of ………. electrons are in stable equilibrium, while in ………. electrons always experience a net force. (Thomson’s model/ Rutherford’s model.)

$(c)$ A classical atom based on ………. is doomed to collapse. (Thomson’s model/ Rutherford’s model.)

$(d)$ An atom has a nearly continuous mass distribution in a ………. but has a highly non-uniform mass distribution in ………. (Thomson’s model/ Rutherford’s model.)

$(e)$ The positively charged part of the atom possesses most of the mass in ………. (Rutherford’s model/both the models.)

An electron makes a transition from orbit $n = 4$ to the orbit $n = 2$ of tha hydrogen atom. The wave number of the emitted radiations ($R =$ Rydberg's constant) will be

Particles used in the Rutherford's scattering experiment to deduce the structure of atoms

The transition from the state $n = 3$ to $n = 1$ in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from