Atoms

The ratio of momentum of the photons of the 1st and 2nd line of Balmer series of Hydrogen atoms is / . The possible values of and are :

1. 27 and 20
2. 3 and 16
3. 5 and 36
4. 20 and 27

In the hydrogen atom, the electron makes a transition from the higher orbit (i) to a lower orbit (f). The ratio of the radius of the orbits is given by ri:rf=16:4. The wavelength of photon emitted due to this transition is nm. (Given Rydberg constant = 1.0973 107 /m)

1. 121
2. 242
3. 486
4. 974

In Rutherford's alpha-particle scattering experiment, only a few alpha particles rebound back because Choose the correct answer from the options given below :

1. A, B Only
2. B, E Only
3. C, D Only
4. A, C, E Only

Angular momentum of an electron in a hydrogen atom is 3h , then the energy of the electron is eV.

1. -1.51
2. -0.85
3. -0.38
4. -0.28

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 .

Two electrons are moving in orbits of two hydrogen-like atoms with speeds 3 105 m/s and 2.5 105 m/s respectively. If the radii of these orbits are nearly same then the possible order of energy states are respectively.

1. 8 and 10
2. 10 and 12
3. 9 and 8
4. 6 and 5

In hydrogen atom spectrum, (R Rydberg's constant) Choose the correct answer from the options given below :

1. A, B Only
2. B, D Only
3. A, B and D Only
4. A, B and C Only

A 7.9 MeV -particle scatters from a target material of atomic number 79. From the given data the estimated diameter of nuclei of the target material is (approximately) m. [ 14 0 = 9 109 N m2/C2 . and electron charge . = 1.6 10-19 C ]

1. 2.88 10-14
2. 5.76 10-14
3. 1.44 10-13
4. 1.69 10-12

The smallest wavelength of Lyman series is 91 nm. The difference between the largest wavelengths of Paschen and Balmer series is nearly nm.

1. 1784
2. 1875
3. 1217
4. 1550

If an alpha particle with energy 7.7 MeV is bombarded on a thin gold foil, the closest distance from nucleus it can reach is m. (Atomic number of gold = 79 and 14 0 = 9 109 in SI units)

1. 2.95 10-16
2. 3.85 10-14
3. 2.95 10-14
4. 3.85 10-16

The energy of an electron in an orbit of the Bohr's atom is -0.04E0 eV where E0 is the ground state energy. If L is the angular momentum of the electron in this orbit and h is the Planck's constant, then 2 Lh is :

1. 6
2. 2
3. 5
4. 4

In a hydrogen like ion, the energy difference between the 2nd excitation energy state and ground is 108.8 eV. The atomic number of the ion is:

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

For a hydrogen atom, the ratio of the largest wavelength of Lyman series to that of the Balmer series is

1. 5 : 27
2. 27 : 5
3. 3 : 4
4. 5 : 36

Considering the Bohr model of hydrogen-like atoms, the ratio of the radius of 5th orbit of the electron in Li2+ and He+ is

1. 32
2. 23
3. 49
4. 94

Given below are two statements : In the light of the above statements, choose the most appropriate answer from the options given below :

1. Both Statement I and Statement II are correct
2. Statement I is correct but Statement II is incorrect
3. Both Statement I and Statement II are incorrect
4. Statement I is incorrect but Statement II is correct

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. In the light of the above statements, choose the correct answer from the options given below

1. A is true but R is false
2. Both A and R are true and R is the correct explanation of A
3. A is false but R is true
4. Both A and R are true but R is NOT the correct explanation of A

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 .

Considering Bohr's atomic model for hydrogen atom : Choose the correct answer from the options given below :

1. (A), (B) only
2. (A), (D) only
3. (A), (C) only
4. (B), (D) only

Assuming the validity of Bohr's atomic model for hydrogen-like ions the radius of Li++ ion in its ground state is given by 1Xa0, where X = (Where a0 is the first Bohr's radius.)

1. 2
2. 9
3. 1
4. 3

The number of spectral lines emitted by atomic hydrogen that is in the 4th energy level, is

1. 3
2. 6
3. 1
4. 0

The frequency of revolution of the electron in Bohr's orbit varies with n, the principal quantum number as:

1. 1n4
2. 1n2
3. 1n3
4. 1n

During the transition of electron from state A to state C of a Bohr atom, the wavelength of emitted radiation is 2000 and it becomes 6000 when the electron jumps from state B to state C. Then the wavelength of the radiation emitted during the transition of electrons from state A to state B is

1. 4000
2. 6000
3. 2000
4. 3000

An electron in the ground state of the hydrogen atom has the orbital radius of 5.3 10-11 m while that for the electron in third excited state is 8.48 10-10 m. The ratio of the de Broglie wavelengths of electron in the ground state to that in the excited state is

1. 4
2. 3
3. 9
4. 16