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#### Quantum Mechanical Model of Atom Creative one mark questions with answer key

11th Standard

Reg.No. :
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Chemistry

Time : 00:40:00 Hrs
Total Marks : 50

Part - A

50 x 1 = 50
1. Schrodinger wave equation is applied to determine______.

(a)

Probability of finding electron at a given point in space

(b)

Wave motion of the electron

(c)

Probability density of electron in a given region

(d)

All of the above

2. Bohr's equation for energy of an election in a hydrogen atom is given as______

(a)

$E=\frac { -1312 }{ { n }^{ 2 } } KJ{ mol }^{ -1 }$

(b)

$E=\frac { -1312 }{ { n }^{ 2 }{ h }^{ 2 } } KJ{ mol }^{ -1 }$

(c)

E = hv

(d)

$E=\frac { 4{ \pi }^{ 2 }{ me }^{ 4 } }{ { n }^{ 2 }{ h }^{ 2 } } KJ{ mol }^{ -1 }$

3. The effect which represents the splitting of spectral lines by external electric field is______

(a)

Stark effect

(b)

Zeeman effect

(c)

Raman effect

(d)

None of these

4. According to Bohr's theory angular momentum of an electron in 6th orbit is

(a)

$2.5\frac { h }{ \pi }$

(b)

$6\frac { h }{ \pi }$

(c)

$3\frac { h }{ \pi }$

(d)

$\frac { 2.5h }{ 2\pi }$

5. When an electron jumps from lower orbit to higher orbit

(a)

energy is released

(b)

energy is absorbed

(c)

no change in energy

(d)

6. Which of the following set of quantum number is possible?

(a)

n=4 l=2 m=-2 s=-2

(b)

n = 4 l=4 m = 0 s=1/2

(c)

n=4 l=3 m= -3 s= 1/2

(d)

n=4 l=0 m=0 s=0

7. What is the maximum number of orbitals that can be identified with the following quantum numbers? n=3,l=1,m1=0

(a)

1

(b)

2

(c)

3

(d)

4

8. Maximum number of electrons in a subshell of an atom is determined by the following

(a)

2l+1

(b)

4l-2

(c)

2n2

(d)

4l+2

9. Who modified Bohr's theory by introducing elliptical orbits for electrons path?

(a)

Rutherford

(b)

Thomson

(c)

Hund

(d)

Sommerfeld

10. The de-Broglie wavelength of a particle with mass 19and velocity 100 m/s is

(a)

6.63 $\times$ 10-35 m

(b)

6.63 $\times$ 10-34 m

(c)

6.63 $\times$ 10-33 m

(d)

6.65 $\times$ 10-35 m

11. Which of the following is not among short comings of Bohr's model?

(a)

Bohr theory could not account for the fine lines in the atomic spectrum

(b)

Bohr theory was unable to account for the splitting of the spectral lines in the presence of magnetic field

(c)

No explanation for using the principle of quantisation of angular momentum

(d)

It did not give information about energy level

12. What will be the wavelength of a ball of mass 0.1 kg moving with a velocity of 10ms-1?

(a)

6.62 $\times$ 10-34m

(b)

6.626 $\times$ 1034m

(c)

6.626 $\times$ 10-34m

(d)

6.626 $\times$ 1034m

13. The de-Broglie wavelength associated with a matter particle is

(a)

Directly proportional to die momentum of the particle

(b)

Directly proportional to the velocity of the particle

(c)

Inversely proportional to the momentum of the particle

(d)

Inversely proportional to Plank's constant

14. The wavelength associated with an electron moving with velocity 1010 ms-1 is

(a)

6.62 $\times$ 10-10 m

(b)

7.28  $\times$ 10-14 m

(c)

3.69 $\times$ 10-12 m

(d)

4.92 $\times$ 10-11 m

15. Electronic configuratton of species M2+ is 1s2 2s2 2p6 3s2 3p6 3d6 and its atomic weight is 56. The number of neutrons in the nucleus of species M is

(a)

26

(b)

22

(c)

30

(d)

24

16. Assertion (A): Isotopes of a given element show the same type of chemical behavior.
Reason (R): The chemical properties of an atom are governed by the number of electrons in the atom.

(a)

Both A and R are true and R is the correct explanation of A

(b)

Both A and R are true but R is not the correct explanation of A

(c)

A is true but R is false

(d)

Both A and R are false

17. Assertion (A): Energy of an electron is taken negative.
Reason (R): Energy of electron at infinity is zero.

(a)

Both A and R are true and R is the correct explanation of A

(b)

Both A and R are true but R is not the correct explanation of A

(c)

Ais true but R is false

(d)

Both A and R are false

18. Assertion (A): Bohr's orbits are also called stationary states.
Reason (R): Electrons are stationary is an orbit.

(a)

Both A and R are true and R is the correct explanation ofA

(b)

Both A and R are true but Ris not the correct explanation of A

(c)

A is true but R is false

(d)

Both A and R are false

19. Assertion (A): Angular momentum of an electron in an atom is quantized
Reason (R): In an atom only those orbits are permitted in which angular momentum of the electron is natural number multiple of $\frac { h }{ 2\pi }$

(a)

Both A and R are true and R is the correct explanation of A

(b)

Both A and R are true but R is not the correct explanation of A

(c)

A is true but R is false

(d)

Both A and R are false

20. Assertion (A): The orbitals having equal energy are known as degenerate orbitals.
Reason (R): The three 2p orbitals are degenerate is the presence of external magnetic field.

(a)

Both A and R are true and R is the correct explanation of A

(b)

Both A and R are true but R is not the correct explanation of A

(c)

A is true but R is false

(d)

Both A and R are false

21. Assertion (A): In a multi-electron atom, the electrons in different subshell have different energies.
Reason (R): Energy of an orbital depends. upon n + l value.

(a)

Both A and R are true and R is the correct explanation of A

(b)

Both A and R are true but R is not the correct explanation of A

(c)

A is true but R is false

(d)

Both A and R are false

22. The speed of light is 3 x 1017 nms -1. Which is the closest to the wavelength in nanometer of a quantum of light with frequency of 6 x 1015 s-1?

(a)

10

(b)

25

(c)

50

(d)

75

23. The velocity of light is 3 x 108 ms-1. The wave length of violet radiation is 400 nm. The wavelength in frequency (Hz) is:

(a)

7.5 x 1014 Hz

(b)

7.5 x 1015 Hz

(c)

7.5 x 1013 Hz

(d)

7.5 x 1016 Hz

24. The energy associated with the first orbit of He+ ion is:

(a)

-8.72 x 1018 J

(b)

8.78 x 1018 J

(c)

8.78 x 10-17

(d)

-8.72 x 10-17 J

25. The radius of the first orbit of He+ ion is:

(a)

0.027 nm

(b)

0.27 nm

(c)

2.7 nm

(d)

0.35 nm

26. Given that the energy of the first Bohr about is -1312 kJ mol-1, the ionisation energy of hydrogen atom is:

(a)

-1312 kJ

(b)

1312 kJ

(c)

21.8 x 10-20 J

(d)

2.18 x 10-19 J

27. The radius of which of the following is same as that of the first Bohr orbit of hydrogen atom?

(a)

He+ (n = 2)

(b)

Li+2 (n = 2)

(c)

Li-2 (n = 3)

(d)

Be+3 (n = 2)

28. ${ \Psi }^{ 2 }$ = 0 represents:

(a)

a node

(b)

an orbital

(c)

angular wave function

(d)

wave function

29. If the de Broglie wavelength of a particle of mass (m) is 100 times its velocity, then its value in terms of its mass (m) and Planck's constant (h) is:

(a)

$\frac{1}{10}\sqrt{\frac{m}{h}}$

(b)

${10}\sqrt{\frac{h}{m}}$

(c)

$\frac{1}{10}\sqrt{\frac{h}{m}}$

(d)

${10}\sqrt{\frac{m}{h}}$

30. For a principle quantum number n = 4, the total number of orbitals having l = 3 is:

(a)

3

(b)

7

(c)

5

(d)

9

31. What is the maximum number of electrons that can be associated with the following set of quantum numbers? n = 3, l = 2, m = + 2.

(a)

1

(b)

2

(c)

3

(d)

4

32. The maximum probability of finding electrons in dxy orbital is:

(a)

along the x-axis

(b)

along the y-axis

(c)

at an angle 45° from the x-axis andy-axis

(d)

at an angle 90° from the x-axis and y-axis

33. The orbital diagram in which both the Pauli's exclusion principle and Hund's rule are violated is:

(a)

(b)

(c)

(d)

34. The angular momentum of an electron is zero. In which orbital it may be present?

(a)

2s

(b)

2p

(c)

3d

(d)

4f

35. Which of the following expressions represents the electron probability function?

(a)

$4\pi r dr{ \Psi }^{ 2 }$

(b)

$4\pi r^2 dr{ \Psi }$

(c)

$4\pi r^2 dr{ \Psi }^{ 2 }$

(d)

$4\pi r dr{ \Psi }$

36. Which of the following has the largest wavelength, provided all have equal velocity?

(a)

carbon di oxide molecule

(b)

electron

(c)

ammonia molecule

(d)

proton

37. The number of planar nodes in an orbital can be determined from the value of:

(a)

principal quantum number (n)

(b)

azimuthal quantum number (l)

(c)

both principal and magnetic quantum number (n, m)

(d)

magnetic quantum number (m)

38. Identify the quantum number for 4dx2-y2.electron.

(a)

$4,2,-2,+\frac{1}{2}$

(b)

$4,0,0,+\frac{1}{2}$

(c)

$4,3,2,+\frac{1}{2}$

(d)

$4,3,2,-\frac{1}{2}$

39. How many orbitals are possible in 3rd energy level?

(a)

16

(b)

9

(c)

3

(d)

27

40. The region where the probability density function of electron reduces to zero is called__________.

(a)

orbit

(b)

orbital

(c)

nodal surface

(d)

subshell

41. Consider the following statements.
(i) The region where the probability density of electron is zero, called nodal surface.
(ii) The probability of finding the electron is independent of the direction of the nucleus.
(iii) The number of radial nodes is equal to n + 1+ 1
Which of the above statements is/are correct?

(a)

(i) and (iii)

(b)

(i) and (ii)

(c)

(iii) only

(d)

(i) and (iii)

42. Match the list-I and list-II correctly using the code given below the list.

 List-I List-II A. orbital 1. complex three dimensional shape B. p - orbital 2. symmetrical sphere C. d - orbital 3. dumb-bell shape D. f - orbital 4. clover leaf shape
(a)
 A B C D 1 4 3 2
(b)
 A B C D 3 1 2 4
(c)
 A B C D 2 3 4 1
(d)
 A B C D 4 2 1 3
43. Which one of the following is the correct increasing order of effective nuclear charge felt by an electron?

(a)

s>p>d>f

(b)

s<p<d<f

(c)

s>p>f>d

(d)

f<p<d<s

44. The value of n, I, m and s of 8th electron in an oxygen atom are respectively____________.

(a)

$1,0,0,+\frac{1}{2}$

(b)

$2,1,+1,-\frac{1}{2}$

(c)

$2,1,-1,-\frac{1}{2}$

(d)

$2,1,0,+\frac{1}{2}$

45. The number of unpaired electrons in carbon atom in the gaseous state is___________.

(a)

0

(b)

1

(c)

2

(d)

3

46. Which of the following is not used in writing electronic configuration of an atom?

(a)

Aufbau principle

(b)

Hund's rule

(c)

Pauli's exclusion principle

(d)

Heisenberg's uncertainty principle

47. Which of the following is the expected configuration of Cr (Z = 24)?

(a)

1s2 2s2 2p6 3s2 3p6 3d4 4s2

(b)

1s2 2s2 2p6 3s2 3p6 3d5 4s1

(c)

1s2 2s2 2p6 3s2 3p6 3d6

(d)

1s2 2s2 2p6 3s2 3p6 3d5 4s3

48. Which of the following experiment proves the presence of an electron in an atom?

(a)

Rutherford's $\alpha$-ray scattering experiment

(b)

Davisson and Germer experiment

(c)

J. J. Thomson cathode ray experiment

(d)

G.P. Thomson gold foil experiment

49. Consider the following statements regarding Rutherford's $\alpha$-ray scattering experiment.
i. Most of the $\alpha$-particles were deflected through a small angle.
ii. Some of $\alpha$-particles passed through the foil.
iii. Very few $\alpha$-particles were reflected back by 180o.
Which of the above statements is/are not correct.

(a)

i and ii

(b)

ii and iii

(c)

i and iii

(d)

i, ii and iii

50. Considering Bohr's model which of the following statements is correct?

(a)

The energies of electrons are continuously reduced in the form of radiation.

(b)

The electron is revolving around the nucleus in a dynamic orbital.

(c)

Electrons can revolve only in those orbits in which the angular momentum (mvr) of the electron must be equal to an integral multiple of h/2$\pi$ .

(d)

In an atom, electrons are embedded like seeds in watermelon.