Atoms

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

An electron of hydrogen atom in an excited state is having energy En=-0.85 eV. The maximum number of allowed transitions to lower energy level is .

An electron revolving in nth Bohr orbit has magnetic moment n. If n nx, the value of x is

1. 2
2. 0
3. 3
4. 1

When a hydrogen atom going from n=2 to n=1 emits a photon, its recoil speed is x5 m/s. Where x= . (Use, mass of hydrogen atom =1.6 10-27 kg)