#### Centum five mark questions in Quantum Mechanical Model of Atom

11th Standard

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Chemistry

Time : 01:40:00 Hrs
Total Marks : 100
Part - A
20 x 5 = 100
1. Enlist the postulates of Bohr's atom model.

2. By applying Bohr's postulates, arrive at the radius of nth orbit for hydrogen like atom

3. Write a note on limitations of Bohr's atom model.

4. Derive an equation for the wavelength of a matter wave.

5. List out the important features of quantum mechanical model of atom

6. How does the effective nuclear charge influence the stability of the orbital?

7. The electronic configuration of Cr and Cu are written as 3d5 4s1 and 3d10 4s1 instead 3d4 4s2 and 3d9 4s2 Justify the statement

8. The quantum numbers of six electrons are given below. Arrange them in order of increasing energies.If any of these combination(s) has/have the same energy lists.
(i) n=4, l=2 m1 = -2,ms= - $\frac { 1 }{ 2 }$
(ii) n= 3, l= 2, m1=1,ms = +$\frac { 1 }{ 2 }$
(iii) n= 3, l= 1,m1 =0 m= +$\frac { 1 }{ 2 }$
(iv) n= 3, l= 2,m1 = -2,ms= - $\frac { 1 }{ 2 }$
(v) n= 3, l= 1,m1=-1,,ms=+ $\frac { 1 }{ 2 }$
(vi) n= 4, l= 1,m1 = 0, ms= +$\frac { 1 }{ 2 }$

9. A neutral atom of an element has 2K, 8L and 5M electrons. Find out the following.
(i) Atomic number of the element  (ii) Total number of s-electrons  (iii) Total number of p-electrons (iv) Number of protons in the nucleus  (v) Valency of the element

10. Determine the following for the fourth shell of an atom.
(a) The number of subshells
(b) The designation for each subshell
(c) The number of orbitals in each subshell
(d) The maximum number of electrons that can be contained in each subshell

11. Calculate the uncertainty in the velocity of a wagon of mass 3000kg whose position is known to an accuracy of ±10 pm.(Planck's constant = 6.626 x 10-34 kg m2 S-1)

12. The uncertainty in the position and velocity of a particle are 10-2 m and $5.27\times { 10 }^{ -24 }{ ms }^{ -1 }$ respectively. Calculate the mass of the particle

13. Calculate the product of the uncertainties of displacement and velocity of a moving electron having a mass of 9.1 X 10-28 g

14. Calculate the uncertainty in position of a dust particle of mass 0.1 mg if the uncertainty in velocity is $5\times { 10 }^{ -19 }{ ms }^{ -1 }$

15. The uncertainty in the position and velocity of a particle are 1 nm and 5.27 X 10-24
ms-1 respectively. Calculate the mass of the particle.

16. A beam of helium atoms moves with a velocity of 2.0 $\times$ 103 ms-1 .Find the wavelength of the particles constituting the beam (h=6.626$\times$10-34 Js)

17. Define the following terms with examples.
(i) Isotopes (ii) Isotones (iii) Isobars (iv) Isoelectronic species (v) Nucleon

18. Complete the table given below

 S.No Symbol Mass No. Atomic No Proton Neutron Electrons 1. Zn2+ 64 30 - - - 2. Cl- 35 - - 18 18 3. Ar - - 18 22 1
19. Calculate the wavelength of the radiations emitted when an electron in a hydrogen atom undergo transition from 4th energy level to the 2nd energy level.

20. Calculate the de Broglie wavelength of an electron that has been accelerated from rest through 1potential differences of 1 KV.