Atoms

Using Bohr's model, calculate the ratio of the magnetic fields generated due to the motion of the electrons in the 2nd and 4th orbits of hydrogen atom .

An electron in the hydrogen atom initially in the fourth excited state makes a transition to nth energy state by emitting a photon of energy 2.86 eV. The integer value of n will be .

In an alpha particle scattering experiment distance of closest approach for the particle is 4.5 10-14 m. If target nucleus has atomic number 80 , then maximum velocity of -particle is 105 m/s approximately. ( 14 0 = 9 109 SI unit, mass of particle = 6.72 10-27 kg)

Radius of a certain orbit of hydrogen atom is 8.48 Å. If energy of electron in this orbit is E/x, then x = (Given a0 = 0.529 Å, E = energy of electron in ground state).

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).

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]

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= .

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 .

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)

Hydrogen atom is bombarded with electrons accelerated through a potential difference of V, which causes excitation of hydrogen atoms. If the experiment is being performed at T=0 K, the minimum potential difference needed to observe any Balmer series lines in the emission spectra will be 10 V, where = .

If Rydberg's constant is R, the longest wavelength of radiation in Paschen series will be 7R, where = .