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#### Creative three mark questions Quantum Mechanical Model of Atom - II

11th Standard

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Chemistry

Answer any 3 of the following questions
Time : 01:30:00 Hrs
Total Marks : 90

Part - A

30 x 3 = 90
1. Explain the shapes of p orbitals

2. Discuss the shapes of d orbitals.

3. Write a note on the shape of f orbitals

4. (i) What is common between dxy and dx2-y2 orbitals?
(ii) What is the difference between them?
(iii) What is the angle between the lobes of the above two orbitals?

5. If the K.E of electron is 2.5 $\times$10-24 J, then calculate its de-Broglie wavelength.

6. Calculate the number of electrons, protons and neutrons in (i) Phosphorous atom (ii) Phosphate ion.

7. In Rutherford's experiment, generally thin foil of heavy atoms, like gold, platinum etc. have been used to bombard the a-particles. If the thin foil of light atoms like aluminum is used, what difference would be observed from the above results?

8. In a chemical reaction, chlorine atom undergoes reduction and aluminium atom undergoes oxidation. Will this redox reaction affect their initial number of protons, neutrons and electrons?

9. Symbols $_{ 35 }^{ 79 }{ Br }$ and 79Br can be written, where as symbols$_{ 79 }^{ 35 }{ Br }$r and 35Br are not acceptable. Answer briefly

10. What is Zeeman effect?

11. What is Stark effect?

12. Explain why are Bohr's orbitals are called energy levels?

13. Orbits are also called as stationary states. Say whether the above statement is true or false.Justify your answer

14. What do you understand by dual character of matter?

15. Two particles A and B are in motion. If the wavelength associated with the particle A is 5 $\times$ 10-8 cm calculate the wavelength of particle B, if its momentum is half of A.

16.  If the velocity of the electron in Bohr's first orbit is $2.19\times { 10 }^{ 6 }{ ms }^{ -1 }$ Calculate the de-Broglie wavelength with it.

17. Calculate the uncertainty in the position of a cricket ball of mas 150g if the uncertainty in velocity is 3.52 $\times$ 10-24 ms-1

18. Which of the following are isoelectronic species? Na+, K+, Mg2+, Ca2+, S2-, Ar.

19. Write the Schrodinger wave equation

20. State Heisenberg's uncertainty principle and give its mathematical expression

21. What are the significance of $\Psi$ and $\Psi ^{ 2 }$

22. How does the Bohr theory of the hydrogen atom differ from that of Schrodinger?

23. Can we apply Heisenberg's uncertainty principle to a stationary electron? Why?

24. Bring out the main points of difference between orbit and orbital.

25. The effect of uncertainty principle is significant only for motion of microscopic particles and is negligible for the macroscopic particles. Justify the statement with the help of a suitable example.

26. Give a brief account of the shapes of atomic orbitals?

27. A golf ball has a mass of 40g and a speed of 45 m/s. If the speed can be measured within accuracy of 2% calculate the uncertainty in position.

28. Calculate the kinetic energy of a moving electron which has a wavelength 4.8 pm. (mass of electron = 9.11 x 10-31 kg, h = 6.63 x 10-34 JS)

29. How many orbitals are possible in the 4th energy level? (n = 4)

30. How many unpaired electrons are present in the ground state of Fe3+ (z=26), Mn2+(z=25) and argon(z=18)?

31. Explain the meaning of the symbol 4f2. Write all the four quantum numbers for these electrons.