Atoms

In the first excited state of hydrogen atom, the energy of its electron is −3.4 eV. The radial distance of the electron from the hydrogen nucleus in this case is approximately : (Take 1 eV = 1.6 10-19 J, e = 1.6 10-19 C and 14 0 = 9 109 N m2/C2)

1. 2.1 10-8 m
2. 2.1 10-10 m
3. 2.1 10-11 m
4. 2.1 10-9 m

Consider that an electron is revolving in an excited state of Hydrogen atom with velocity 25.6 105 ms-1. The radius of the orbit is x 10-9 m. The value of x is: [Take the mass of electron to be 9 10-31 kg, charge of electron = -1.6 10-19 C and 14 0 = 9 109 Nm2C-2]

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

In Geiger-Marsden experiment, the number of scattered -particles N( ) is plotted as a function of scattering angle . Which of the following options represents the correct plot?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

A particle of mass m is moving around the origin with a constant force F pulling it towards the origin. If Bohr model is used to describe its motion, the radius of the nth orbit and the particle's speed v in the orbit depend on n as

1. r n2/3; v n1/3
2. r n4/3; v n-1/3
3. r n1/3; v n1/3
4. r n1/3; v n2/3

De-Broglie wavelength of an electron orbiting in the n = 2 state of hydrogen atom is close to (Given Bohr radius = 0.052 nm)

1. 1.67 nm
2. 2.67 nm
3. 0.067 nm
4. 0.67 nm

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

Match List I with List II: Choose the correct answer from the options given below:

1. A-II, B-I, C-IV, D-III
2. A-III, B-IV, C-II, D-I
3. A-IV, B-III, C-I, D-II
4. A-I, B-II, C-III, D-IV

The spectral series which corresponds to the electronic transition from the levels n2 = 5, 6, to the level n1 = 4 is

1. Pfund series
2. Brackett series
3. Lyman series
4. Balmer series

Some energy levels of a molecule are shown in the figure with their wavelengths of transitions. Then : [figure]

1. 3 > 2, 1 = 2 2
2. 3 > 2, 1 = 4 2
3. 1 > 2, 2 = 2 3
4. 2 > 1, 2 = 2 3

In hydrogen spectrum, the shortest wavelength in the Balmer series is . The shortest wavelength in the Brackett series is :

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