#### Most important two mark questions in Quantum Mechanical Model of Atom

11th Standard

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Chemistry

Time : 00:50:00 Hrs
Total Marks : 50

Part - A

25 x 2 = 50
1. Write a note on Thomson's plum pudding model of an atom.

2. What did Rutherford's alpha ray scattering experiment prove

3. What are the defects of Rutherford's model?

4. What is the charge and mass of an electron?

5. What is the difference between atomic mass and mass number?

6. Give the number of electrons in the following species. H2 , H2 , O2 and O2-

7. How many neutrons and protons are there in the Following nuclei?
$_{ 6 }^{ 13 }{ C }$,$_{ 2 }^{ 18 }{ O }$.$_{ 12}^{ 24}{ Mg }$,$_{26 }^{ 56}{ Fe }$,$_{ 88}^{ 38}{ Sr }$

8. After the execution of the $\alpha$-ray scattering experiment, what were the observations made by Rutherford? What did he conclude from his observations?

9. Write the values of all the four quantum numbers for all the electrons present in hydrogen and Helium atoms.

10. Write the values of four quantum numbers present in the last electron in, an atom having the electronic configuration
(i) 1s2 2s2 2p1
(ii) 1s2 2s2 2p6 3s2 3p2.

11. How many electrons are present in all subshells (fully filled) with n + l = 5?

12. Why Pauli exclusion principle is called exclusion principle?

13. At what distance is the radial probability maximum for 1s orbital? What is this distance called?

14. Bring out the similarities and dissimilarities between a 1s and 2s orbital.

15. How many radial / spherical nodes will be present in 5f orbital?

16. For each of the following pair of hydrogen orbitals indicate which is higher in energy?
(i) 1s, 2s
(ii) 2p, 3p
(iii) 3dxy 3dyz
(iv) 3s, 3d
(v) 4f, 5s.

17. How many electrons in sulphur (z = 16) can have n + I = 3?

18. The ground state electronic configurations listed below here are incorrect. Explain what mistakes have been made in each and correct the electronic configuration.
(i) Al = 1s2 2s2 2p4 3s2 3p6 .
(ii) B = 1s2 2s2 2p5
(iii) F = 1s2 2s2 2p5.

19. What is the angular momentum of an electron in (i) 2s orbital (ii) 4f orbital?

20. Draw the shapes (boundary surfaces) for the following orbitals.
(i) 2px
(ii) 3dz
(iii) 3dx2y2

21. Chromium (Z = - 24) and copper (Z = 29), should have the configuration.
Cr = 1s2 2s2 2p3s2 3p6 3d4s2
Cu = 1s2 2s2 2p6 3s2 3p6 3d9 4s2
But their actual configuration are    Cr = 1s2 2s2 2p3s2 3p6 3d5 4s1 and
Cu = 1s2 2s2 2p3s2 3p6 3d10 4s1 Explain the reason.

22. Calculate the wave length of an electron (mass = 9.1 x 10-31 kg) moving with 'a velocity of 10ms-1 (h = 6.6 x 10-34 kg m2 sec-1).

23. The kinetic energy of a subatomic particle is 5.58 x 10-25 J. Calculate the frequency of the particle wave. (Planck's constant h = 6.626 x 10-34 kg m2 s-1)

24. A microscope using suitable photons is employed to locate an electron in an atom within a distance of 0.1$\overset { o }{ A }$  What is the uncertainty involved in the measurement of its velocity.

25. Energy of an electron in hydrogen atom in ground state is -13.6 eV. What is the energy of the electron in the second excited state?