FSC Physics MCQs Chapter 20 Class 12

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Physics Ch 20 Class 12 Atomic Spectra

1 / 61

The anti-particle of quark is _________.

PMC Practice 5
Physics
Atomic Spectra
Elimination Tool:

A) Electrons

B) Protons

C) Neutrons

D) None of these options is correct

2 / 61

The ratio of mass of electron to neutron is:

PMC Practice 4
Physics
Atomic Spectra
Elimination Tool:

A) 1

B) 1200

C) 1300

D) None of these

3 / 61

Which of the following statements is not consistent with Bohr’s set of postulates regarding the hydrogen atom model with regard to the emission and absorption of light?

NTS 2013
Physics
Atomic Spectra
Elimination Tool:

A) Energy levels of the electrons are stable and discrete.

B) An electron emits or absorbs radiation only when making a transition from one energy level to another.

C) To jump from lower energy to higher energy, an electron must absorb a photon of precisely the right frequency such that the photon’s energy equals the energy difference between the two orbits.

D) To jump from a higher energy to a lower energy, an electron’ absorbs a photon of frequency such that photon’s energy is exactly the energy difference between the two orbits.

4 / 61

Find the longest wavelength in the Paschen series, given R = 1.097 x 107m-1.

NUMS 2019 Reconduct
Physics
Atomic Spectra
Elimination Tool:

A) 11097 A

B) 18750 A

C) 17884 A

D) 19001 A

5 / 61

Lifetime of an excited state is

PMC Sample 3
Physics
Atomic Spectra
Elimination Tool:

A) 10^(-6)s

B) 10^(-7)s

C) 10^(-8)s

D) 10^(-3)s

6 / 61

The wavenumber of a photon in Brackett series is 9/400 R then electron transited from orbit with the quantum number:

PMC Sample 2
Physics
Atomic Spectra
Elimination Tool:

A) n=3

B) n=2

C) n=4

D) n=5

7 / 61

Energy difference in balmer series for longest wavelength is

PMC Sample 3
Physics
Atomic Spectra
Elimination Tool:

A) 1.89 eV

B) 2.9eV

C) 5.6eV

D) 7.8 eV

8 / 61

The wavelength of X-rays is:

10^-10

10^-8

10^-4

10^-12

9 / 61

According to Bohr’s theory of Hydrogen atom, only those atomic orbits with radii ‘r’ and atomic shell ‘n’ around the nucleus are allowed which have the angular moments:

NTS 2016 DUHS & JSMU
Physics
Atomic Spectra
Elimination Tool:

A) rh / 2π

B) nh / 2π

C) 2πn / h

D) 2πr / h

10 / 61

The ratio of wavelength of last line of Balmer series and last line of lymen series is

PMC Sample 2
Physics
Atomic Spectra
Elimination Tool:

A) 2

B) 1

C) 4

D) 0.05

11 / 61

The down quark has charge ________.

PMC Practice 5
Physics
Atomic Spectra
Elimination Tool:

A) -1/2

B) +1/2

C) -1/3

D) +2/3

12 / 61

The nucleus shape is considered to be:

PMC Practice 4
Physics
Atomic Spectra
Elimination Tool:

A) Square

B) Rectangle

C) Sphere

D) Circular

13 / 61

The phenomenon in which certain elements emit invisible radiations is called:

NTS 2018
Chemistry
Atomic Spectra
Elimination Tool:

A) Spectroscopy

B) Radioactivity

C) Gravimetery

D) Chromatography

14 / 61

A particle of mass 5 mg moves with a speed of 8 m/s. Calculate its de Broglie wavelength (h = 6.63 x 10-34 Js)

NTS 2015 DUHS and JSMU
Physics
Atomic Spectra
Elimination Tool:

A) 0.71 x 10-29 m

B) 1.66 x 1029 m

C) 1.66 x 10-29 m

D) 3.77 x 10-29 m

15 / 61

The ionization energy of hydrogen is:

13.6 ev

13.61 J

14 J

13.6 meV

16 / 61

The penetrating power of X rays increases with:

NUMS 2018
Physics
Atomic Spectra
Elimination Tool:

A) Decrease in velocity

B) Increase in frequency

C) Increase in velocity

D) Decrease in their intensity

17 / 61

Total energy of an electron in hydrogen atom when it Jumps to higher orbit from a lower orbit Is

Less negative

More positive

Less positive

Remains same

18 / 61

Radiations emitted by human body lie in which of the following series?

Bracket

Pfund

Paschen

None of these

19 / 61

The shortest wavelength photon emitted in Balmer series is:

NTS 2012
Physics
Atomic Spectra
Elimination Tool:

A) 1.0974 nm

B) 4 nm

C) 364.6 nm

D) 3.64 m

20 / 61

If the ionization energy of a hydrogen atom is 13.6 eV, its ionization potential will be:

PMC Sample 1
Physics
Atomic Spectra
Elimination Tool:

A) 13.6 V

B) 136.0 V

C) 3.4 V

D) None of these options are correct

21 / 61

If the wavelength of K X-ray from Cu is 1.337 x 10-10m, then the energy difference between two levels from which transition results will be:

NUMS 2019 Cancelled
Physics
Atomic Spectra
Elimination Tool:

B) 9.90 KeV

C) 90.3 KeV

D) 8.03 KeV

E) 93.8 KeV

22 / 61

Calculate the energy of a photon of wavelength 6600 angstroms.

PMC Sample 3
Physics
Atomic Spectra
Elimination Tool:

A) 0.3×10^-19J

B) 3×10^-19J

C) 30×10^-19J

D) 300 x 10^-19J

23 / 61

Consider the spectral line resulting from the transition from n=2 to n=1, in atoms and ions given below. The shortest wavelength is produced by:

PMC Sample 3
Physics
Atomic Spectra
Elimination Tool:

A) Hydrogen atom

B) deutirium

C) singly ionised helium

D) doubly ionised helium

24 / 61

_____ are such nuclei of an element that have the same mass number A, but have different charge number Z.

PMC Practice 4
Physics
Atomic Spectra
Elimination Tool:

A) Isotopes

B) Isobars

C) Isomers

D) Isotherms

25 / 61

A star moving away from earth shows?

PMC Practice 5
Physics
Atomic Spectra
Elimination Tool:

A) Green shift

B) Red shift

C) Blue shift

D) None of these options is correct

26 / 61

For the first time in 1914, Henry Moseley used X-rays for the determination of:

NTS 2018
Chemistry
Atomic Spectra
Elimination Tool:

A) Atomic Number

B) Atomic Mass

C) Molecular Mass

D) Equiavalent mass

27 / 61

Bright Lines in pattern show:

PMC Practice 5
Physics
Atomic Spectra
Elimination Tool:

A) Absorption

B) Emission

C) Release

D) Free particle

28 / 61

Which of the following is different for isotopes?

PMC Practice 3
Physics
Atomic Spectra
Elimination Tool:

A) Neutrons

B) Protons

C) Electrons

D) All of these options are correct

29 / 61

In hydrogen spectrum If nj = 6, then the spectral lines lie In:

Balmer Series

Paschen Series

Pfund Series

Humphreys series

30 / 61

Energy of the 4th orbit in a hydrogen atom is:

PMC Sample 1
Physics
Atomic Spectra
Elimination Tool:

A) -2.51 eV

B) -3.50 eV

C) -13.6 eV

D) -0.85 eV

31 / 61

When describing the isotopes of the same element, the most accurate statement is that they have:

NTS 2017
Physics
Atomic Spectra
Elimination Tool:

A) the same spin

B) the same atomic mass but different atomic numbers

C) the same atomic number but different atomic masses

D) the same chemical properties and therefore can not be separated

32 / 61

Spectral lines is like a __________ of absorbed or emission energy in a spectrum.

PMC Sample 3
Physics
Atomic Spectra
Elimination Tool:

A) Charged pattern

B) Fingerprint pattern

C) Discharged pattern

D) None of these options is correct

33 / 61

The formula for the Paschen series for the Hydrogen spectrum is _______.

NTS 2019
Physics
Atomic Spectra
Elimination Tool:

A) 1/λ=Rh(1/22 – 1/n2 ) n=3,4,5

B) 1/λ=Rh(1/42- 1/n2) n=2,3,4,5

C) 1/λ=Rh(1/42- 1/n2 ) n=5,6,7

D) 1/λ=Rh(1/32- 1/n2 ) n=4,5,6

34 / 61

If an electron jumps from 68′ orbit to 7 orbit, the increase in radius will be:

90%

25%

33%

17%

35 / 61

X Ray ______ causes damage to living tissues. As X rays are absorbed in tissues, they break molecular bonds and create reactive free radicals (such as H and OH).

NUMS 2017
Physics
Atomic Spectra
Elimination Tool:

A) Neutrons

C) Electrons

B) Photons

D) Neons

36 / 61

If the ionization energy of hydrogen atom is 13.6 eV, its ionization potential will be

PMC Sample 3
Physics
Atomic Spectra
Elimination Tool:

A) 13.6 eV

B) 136.0 eV

C) 3.4 eV

D) none of these

37 / 61

An atom would be neutral if it has equal number of:

PMC Practice 5
Physics
Atomic Spectra
Elimination Tool:

A) Charged particles

B) Uncharged particles

C) Neutrons

D) All of these options are correct

38 / 61

The velocity of X rays is equal to that of:

NUMS 2018
Physics
Atomic Spectra
Elimination Tool:

A) Speed of sound

B) Speed of electron

C) Speed of alpha – particles

D) Speed of light and gamma rays

39 / 61

________ are very high energy electromagnetic radiations of the extremely short wavelength emitted from the nuclei of radioactive atoms originating from the high energy transitions of the nucleons in the nuclei.

NTS 2015 DUHS and JSMU
Physics
Atomic Spectra
Elimination Tool:

A) Alpha rays

B) Beta rays

C) Gamma rays

D) Electromagnetic rays

40 / 61

Which series is emitted when electron Jumps from a higher orbit to fifth orbit?

Lyman

Balmer

Pfund

Brackett

41 / 61

Spectra corresponding to the sodium vapour lamp is:

PMC Practice 5
Physics
Atomic Spectra
Elimination Tool:

A) Band spectra

B) Line spectra

C) Emission spectra

D) Absorption spectra

42 / 61

The target in the X ray unit is given a:

NUMS 2018
Physics
Atomic Spectra
Elimination Tool:

A) Zero potential

B) High negative potential

C) Low negative potential

D) Positive potential

43 / 61

A hydrogen atom in its ground state absorbs 10.2 eV of energy. What is the orbital angular momentum is increased by?

PMC Sample 3
Physics
Atomic Spectra
Elimination Tool:

A) 4.22×10^-34 Js

B) 2.11×10^-34 Js

C) 3.16×10^-34 Js

D) 1.05×10^-34 Js

44 / 61

Transition of electrons should occur between which orbitals(n) that will emit the longest wavelength in the Balmer series of Hydrogen.

NUMS 2019 Reconduct
Physics
Atomic Spectra
Elimination Tool:

A) 2 to 3

B) 3 to 2

C) 5 to 4

D) 6 to 2

45 / 61

X rays are similar in nature to:

NUMS 2018
Physics
Atomic Spectra
Elimination Tool:

A) Cathode rays

B) Canal rays

C) Gamma rays

D) Beta rays

46 / 61

The ratio of wavelengths of the last line of Balmer series and the last line of Lyman series is:

PMC Sample 2
Physics
Atomic Spectra
Elimination Tool:

A) 0.5

B) 2

C) 1

D) 4

47 / 61

For gaining an atomic spectra, an evacuated glass tube is filled with:

NUMS 2020
Physics
Atomic Spectra
Elimination Tool:

A) Neon

B) Hydrogen

C) Carbon dioxide

D) Sulphur dioxide

48 / 61

A nucleus consists of 19 protons and 20 neutrons. The conventional symbol of this nucleus is:

NTS 2013
Physics
Atomic Spectra
Elimination Tool:

A) 11 Na 12

B) 19 K 19

C) 19 K 39

D) 19 K 20

49 / 61

X-rays are also known as:

NTS 2015 DUHS and JSMU
Physics
Atomic Spectra
Elimination Tool:

A) Rydberg rays

B) Roentgen rays

C) Ultraviolet rays

D) Zig-zag rays

50 / 61

When an electron jumps from outer to 5th orbit, then the spectral lines fall into region.

Lyman

Balmer

Pfund

None of these .

51 / 61

In hydrogen spectrum, Lyman and Balmer series belong to which region?

) Lyman = Visible, Balmer = Ultraviolet

Lyman = Ultraviolet, Balmer = Visible

Lyman = Infrared, Balmer = Ultraviolet

None of the

52 / 61

X rays are affected by:

NUMS 2018
Physics
Atomic Spectra
Elimination Tool:

A) Electric field only

B) Magnetic field only

C) Electric and magnetic field

D) None of these

53 / 61

An electron cannot reside inside a nucleus is explained by:

PMC Practice 5
Physics
Atomic Spectra
Elimination Tool:

A) Compton effect

B) Photoelectric effect

C) Zeeman effect

D) Uncertainty principle

54 / 61

The number of protons in the nucleus is called _____ number.

PMC Sample 3
Physics
Atomic Spectra
Elimination Tool:

A) atomic

B) charge

C) atomic or charge

D) neither atomic nor charge

55 / 61

Electrons are emitted in the production of X rays by:

NUMS 2016
Physics
Atomic Spectra
Elimination Tool:

A) Conduction

B) Convection

C) Thermionic emission

D) None of these

56 / 61

During the production of x-rays, the cathode and anode are enclosed inside an evacuated glass chamber and a high DC voltage of the order of:

NUMS 2020
Physics
Atomic Spectra
Elimination Tool:

A) 1,000 V is maintained

B) 10,000 V is maintained

C) 25,000 V is maintained

D) 50,000 V is maintained

57 / 61

If a proton, alpha particle, and photon moving with the same velocity enter a uniform magnetic field, then which particle will deflect more?

PMC Practice 3
Physics
Atomic Spectra
Elimination Tool:

A) Proton

B) Alpha particle

C) Photon

D) All of these options are correct

58 / 61

The atomic spectra deals with the measurement of?

NTS 2014
Physics
Atomic Spectra
Elimination Tool:

B) Intensities of electromagnetic radiations emitted by atoms

C) Intensities of electromagnetic radiations absorbed by atoms

A) Wavelengths

D) All of these options

59 / 61

The first excitation energy of H atom will be:

NUMS 2015
Physics
Atomic Spectra
Elimination Tool:

A) 10.2 eV

B) 3.4 eV

C) -136 eV

D) 13.6 eV

60 / 61

If an electron undergoes transition from 4th to 2nd orbit, then the color of radiations produced will be:

Violet

Blue-Green

Ultraviolet

Red

61 / 61

Laser light is

Monochromatic

Intense

Coherent

All of these

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FSC Physics MCQs Chapter 20 Class 12

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FSC Physics MCQs Chapter 20 Class 12

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