Atoms

In Franck-Hertz experiment, the first dip in the current-voltage graph for hydrogen is observed at 10.2 V. The wavelength of light emitted by hydrogen atom when excited to the first excitation level is nm. (Given hc = 1245 eV nm, e = 1.6 10-19 C).

An electron rotates in a circle around a nucleus having positive charge Ze. Correct relation between total energy (E) of electron to its potential energy (U) is :

1. 2E = 3U
2. E = U
3. 2E = U
4. E = 2U

The angular momentum of an electron in a hydrogen atom is proportional to : (Where r is the radius of orbit of electron)

1. 1r
2. 1 r
3. r
4. r

The shortest wavelength of the spectral lines in the Lyman series of hydrogen spectrum is 915 Å. The longest wavelength of spectral lines in the Balmer series will be Å.

A hydrogen atom changes its state from n=3 to n=2. Due to recoil, the percentage change in the wavelength of emitted light is approximately 1 10-n. The value of n is . [Given Rhc=13.6 eV, hc=1242 eV nm, h=6.6 10-34 J s, mass of the hydrogen atom =1.6 10-27 kg]

According to Bohr's theory, the moment of momentum of an electron revolving in 4th orbit of hydrogen atom is:

1. 2 h
2. h2
3. h
4. 8 h

The minimum energy required by a hydrogen atom in ground state to emit radiation in Balmer series is nearly :

1. 13.6 eV
2. 1.5 eV
3. 12.1 eV
4. 1.9 eV

A particular hydrogen-like ion emits the radiation of frequency 3 1015 Hz when it makes transition from n=2 to n=1. The frequency of radiation emitted in transition from n=3 to n=1 is x9 1015 Hz, when x= .

If the wavelength of the first member of Lyman series of hydrogen is . The wavelength of the second member will be

1. 275
2. 527
3. 2732
4. 3227

The ratio of the magnitude of the kinetic energy to the potential energy of an electron in the 5th excited state of a hydrogen atom is :

1. 4
2. 1
3. 12
4. 14