#### Quantum Mechanical Model of Atom important five mark questions

11th Standard

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Chemistry

Answer any ten of the following questions
Time : 00:50:00 Hrs
Total Marks : 50
Part - A
10 x 5 = 50
1. If an electron is moving with a velocity 600 ms-1 which is accurate upto 0.005%, then calculate the uncertainty in its position. (h = 6.63 x 10-34 Js. mass of electron = 9.1 x 10-31 kg)

2. Light of wavelength 12818 $\overset { o }{ A }$ is emitted when the electron of a hydrogen atom drops from 5th to 3rd orbit. Find the wavelength of a photon emitted when the electron falls from 3rd to 2nd orbit.

3. Calculate the de Broglie wavelength of an electron that has been accelerated from rest through a potential difference of 1 keV.

4. Calculate the uncertainty in the position of an electron, if the uncertainty in its velocity is 5.7 x 105 ms-1.

5. Calculate the total number of angular nodes and radial nodes present in 3d and 4f orbitals.

6. Explain about (i) Magnetic quantum number (ii) Spin quantum number

7. Explain about the shape of orbitals.

8. What is exchange energy? How it is related with stability of atoms? Explain with suitable examples.

9. Describe about Bohr atom model.

10. Derive de Broglie equation and give its significance.

11. What are the main features of quantum mechanical model of an atom.