The frequency Of radiation emitted during the transition of an electron from a second excited state to a first excited state in H-atom is ${\mathrm{f}}_0.$ The frequency of the same transition emitted by a singly ionized He ion is

1.  $2{\mathrm{f}}_0$

2.  $4{\mathrm{f}}_0$

3.  $\frac{{\mathrm{f}}_0}{2}$

4.  $\frac{{\mathrm{f}}_0}{4}$

When neutron moving with Kinetic Energy 2eV collides with 

stationary $H_1^1$ in the ground state, the collision will be:

1.  Must be elastic

2.  may be inelastic

3.  Both

4.  Must be perfectly inelastic

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

(1) $\frac{16}{25}\lambda$               

(2) $\frac{9}{16}\lambda$

(3) $\frac{20}{7}\lambda$               

(4) $\frac{20}{13}\lambda$

Whose atomic model describes electrons being embedded in a gel of positive charge?

The ratio of longest wavelengths corresponding to Lyman and Balmer series in hydrogen spectrum is

(1)5/27

(2)3/23

(3)7/29

(4)9/31

Out of the following which one is not a possible energy for a photon to be emitted by hydrogen atom according to Bohr's atomic model?

(1)1.9eV                                         

(2)11.1eV

(3)13.6eV                                       

(4)0.65eV

The electron in the hydrogen atom jumps from excited state $\left(n=3\right)$ to its ground state $\left(n=1\right)$ and the photons thus emitted irradiate a photosensitive material. If the work function of the material is $5.1 \mathrm{eV},$ the stopping potential is estimated to be (the energy of the electron in the nth state ${\mathrm{E}}_{\mathrm{n}}=-\frac{13.6}{{\mathrm{n}}^2}\mathrm{eV}$)

1. $5.1 \mathrm{V}$                                               2. $12.1 \mathrm{V}$

3. $17.2 \mathrm{V}$                                              4. $7 \mathrm{V}$

The ionization energy of the electron in the hydrogen atom in its ground state is 13.6 eV. The atoms are excited to higher energy levels to emit radiations of 6 wavelengths. Maximum wavelength of emitted radiation corresponds to the transition between

(a) n=3 to n=2 states

(b) n=3 to n=1 states

(c) n=2 to n=1 states

(d) n=4 to n=3 states

The ratio of specific charge of an $\mathrm{\alpha }$-particle to that of a proton is 
(1) 2 : 1                     

(2) 1 : 1
(3) 1 : 2                     

(4) 1 : 3

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