The Rutherford $α -$particle experiment shows that most of the $α -$particles pass through almost unscattered while some are scattered through large angles. What information does it give about the structure of the atom?

In a Rutherford scattering experiment when a projectile of charge $Z_1$ and mass $M_1$ approaches a target nucleus of charge $Z_2$
 and mass $M_2$ the distance of the closest approach is $r_0.$ What is the energy of the projectile?

A beam of fast-moving alpha particles was directed towards a thin film of gold. The parts $A', B',$ and $C'$ of the transmitted and reflected beams corresponding to the incident parts $A,B$ and $C$ of the beam, are shown in the adjoining diagram. The number of alpha particles in:

What is the ratio of the speed of an electron in the first orbit of an $\mathrm{H}\text-$atom to the speed of light?

The total energy of an electron in the first excited state of a hydrogen atom is about $-3.4~\text{eV}.$ Its kinetic energy in this state will be:
1. $-6.8~\text{eV}$
2. $3.4~\text{eV}$
3. $6.8~\text{eV}$
4. $-3.4~\text{eV}$

In the $n^{th}$ orbit, the energy of an electron is $E_{n}=-\frac{13.6}{n^2} ~\text{eV}$ for the hydrogen atom. What will be the energy required to take the electron from the first orbit to the second orbit?
1. $10.2~\text{eV}$
2. $12.1~\text{eV}$
3. $13.6~\text{eV}$
4. $3.4~\text{eV}$

If an electron in a hydrogen atom jumps from the $3$rd orbit to the $2$nd orbit, it emits a photon of wavelength $\lambda$. What will be the corresponding wavelength of the photon when it jumps from the $4^{th}$ orbit to the $3$rd orbit?