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

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Questions:

Multiple Choice Question

44 x 1 = 44

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.

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 180^o.
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

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

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

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

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

(a)

(b)

(c)

(d)

The value of n, I, m and s of 8^th 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)

\(2,1,0,+\frac{1}{2}\)

Which one of the following is the correct increasing order of effective nuclear charge felt by an electron?

(a)

s > p > d > f

(b)

(c)

s > p > f > d

(d)

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

10.

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)

11.

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

(a)

orbit

(b)

orbital

(c)

nodal surface

(d)

subshell

12.

How many orbitals are possible in 3^rd energy level?

(a)

(b)

(c)

(d)

13.

Identify the quantum number for 4d_x²-y².electron ____________

(a)

\(4,2,-2,+\frac{1}{2}\)

(b)

\(4,0,0,+\frac{1}{2}\)

(c)

\(4,3,2,+\frac{1}{2}\)

(d)

\(4,3,2,-\frac{1}{2}\)

14.

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)

15.

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

16.

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)

\(4\pi r dr{ \Psi }\)

17.

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

(a)

(b)

(c)

(d)

18.

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

(a)

(b)

(c)

(d)

19.

The maximum probability of finding electrons in d_xy 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

20.

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)

(b)

(c)

(d)

21.

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

(a)

(b)

(c)

(d)

22.

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)

\({10}\sqrt{\frac{m}{h}}\)

23.

\({ \Psi }^{ 2 }\) = 0 represents:

(a)

a node

(b)

an orbital

(c)

angular wave function

(d)

wave function

24.

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)

25.

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

26.

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

27.

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

28.

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

29.

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)

(b)

(c)

(d)

30.

Electronic configuration 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)

(b)

(c)

(d)

31.

The wavelength associated with an electron moving with velocity 10¹⁰ ms^-1 is ___________

(a)

6.62 \(\times\) 10^-10m

(b)

7.28 \(\times\) 10^-14m

(c)

3.69 \(\times\) 10^-12m

(d)

4.92 \(\times\) 10^-11m

32.

The de-Broglie wavelength associated with a matter particle is ______________

(a)

Directly proportional to the 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

33.

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

34.

Which of the following is not among shortcomings 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

35.

The de-Broglie wavelength of a particle with mass 19 and 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

36.

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

(a)

Rutherford

(b)

Thomson

(c)

Hund

(d)

Sommerfeld

37.

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

38.

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

(a)

(b)

(c)

(d)

39.

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

40.

When an electron jumps from lower orbit to higher orbit _________

(a)

energy is released

(b)

energy is absorbed

(c)

no change in energy

(d)

it radiates energy

41.

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

(a)

\(2.5\frac { h }{ \pi } \)

(b)

\(6\frac { h }{ \pi } \)

(c)

\(3\frac { h }{ \pi } \)

(d)

\(\frac { 2.5h }{ 2\pi } \)

42.

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

43.

Bohr's equation for energy of an electron 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)

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

44.

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

Assertion and reason

6 x 2 = 12

45.

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.
Codes:
(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

(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

46.

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.
Codes:
(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

(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

47.

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 \(\frac { h }{ 2\pi } \)
Codes:
(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

(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

48.

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

(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

49.

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

(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

50.

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.
Codes:
(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

(a)

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

(b)

A is true but R is false

(c)

Both A and R are false

(d)

Both A and R are false

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Answers Key:

Multiple Choice Question

44 x 1 = 44

(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\(\pi\) .