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Free Atomic Spectra MCQs with Answers

356 Atomic Spectra MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.

Atoms emit or absorb light at specific wavelengths because electrons occupy quantized energy levels and change levels by absorbing or releasing photons. The topic covers emission and absorption spectra, spectral series, hydrogen’s line spectrum, energy-level transitions, and the relation between wavelength, frequency and photon energy.

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356 questions · page 5 of 18

81. An electron can stay in metastable state for:

  • A. 10-8s
  • B. 10-5s
  • C. 10-3s
  • D. None of the above

Explanation: An electron in a metastable state can remain there for a relatively long time, typically around 10⁻³ seconds, because transitions from…

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Correct answer: 10-3s

82. Electrons are emitted in the production of X-rays by the process of:

  • A. Conduction
  • B. Convection
  • C. Thermionic emission
  • D. None of the above

Explanation: Electrons are emitted in the production of X-rays by heating a filament and this process is called thermionic emission and electrons…

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Correct answer: Thermionic emission

83. 1/λn = R [1/p2 - 1/n2] in this relation p= 1, 2, 3...... and n will be:

  • A. P, P+1, P+2....
  • B. P+1, P+2....
  • C. P, P -1, P-2....
  • D. P-1, P-2....

Explanation: We know 1/λn = R [1/p2 - 1/n2] where p is lower state and n is higher state.So, n = p+1Electrons move from one state to another higher one…

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Correct answer: P+1, P+2....

84. Each sentence below has a blank indicating that something has been omitted. Choose the word that best fits in with the meaning of the sentence as a whole.Because the soldier loved his country, he refused to _ national secrets to his enemy.

  • A. Divulge
  • B. Localise
  • C. Innovate
  • D. Obliterate

Explanation: Divulge means to make information known or public, especially something secret or private, which is appropriate for the context of not…

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Correct answer: Divulge

85. Spot the error. Because we had an accident on our car last year, I and Lauren had to pull out shortly before the event.

  • A. Because we
  • B. on our car
  • C. I and Lauren
  • D. pull out

Explanation: The error in the sentence is in option (C) "I and Lauren," which should be corrected to "Lauren and I" to maintain proper grammatical order.

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Correct answer: I and Lauren

86. In this section of logical deduction, the question consists of a brief passage (usually a report containing certain data regarding some social or economic problem), followed by certain inferences based on it. The student is required to analyze the contents (or data) of the passage and grasp the desirable facts from it. Then, student has to consider each of the given inferences in the context of the given passage. decide upon its degree of truth or falsity and then choose the hest alternative provided accordingly.Though the State cultivates only 3.2 lakh tons of mangoes. they are of premium quality and with mangoes becoming second most consumed fruit in the world after grapes, the government has been trying exporting it through sea route which is cheaper. An experiment which was done in this regard last year hasred successful.Most of the other exports are though sea routes which is cheaper.

  • A. Definitely true
  • B. Probably true
  • C. Data inadequate
  • D. Probably false
  • E. Definitely false

Explanation: The correct answer is 'Probably true' because the passage provides evidence supporting the likelihood of continued mango exports via the…

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Correct answer: Probably true

87. In this question, a statement is given followed by two courses of action numbered I and II. It is required to grasp the statement, analyze the problem or policy it mentions and then decide which of the courses of action logically follow / most appropriate.Statement:Courts take too long in deciding important disputes of various departments.Courses of action:I) Courts should be ordered to speed up matters.II) Special powers should be granted to officers to settle disputes concerning their department.

  • A. If only I is most appropriate
  • B. If only II is most appropriate
  • C. If either I or II is most appropriate
  • D. If neither I nor II is most appropriate
  • E. If both I and II are most appropriate

Explanation: The main issue is the lengthy time courts take to resolve departmental disputes.

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Correct answer: If only II is most appropriate

88. Directions: In the following question, a number sequence is given with one term missing. Choose the correct term that will continue the same pattern and replace the question mark in the given sequence.45,54,47,?,49,56,51,57,53

  • A. 48
  • B. 50
  • C. 55
  • D. 60

Explanation: The sequence 45, 54, 47, ?, 49, 56, 51, 57, 53 can be divided into two interleaved patterns.

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Correct answer: 55

89. In the following question, two statements numbered I and II are given. There may be cause and effect relationship between the two statements. These two statements may be the effect of the same cause or independent causes. These statements may be independent causes without saving any relationship. Read both the statements in question and mark your answer as:A. If statement I is the cause and statement II is its effect;B. If statement II is the cause and statement, I is its effect;C. If both the statements I and II are independent causes;D. If both the statements I and II are effects of independent causes;E. If both the statements I and II are effects of some common causes;I. The employees of the biggest bank in the country have given an indefinite strike call starting from third of the next month.II. The employees of the Federal Government have withdrawn their week-long demonstrations.

  • A. A. If statement I is the cause and statement II is its effect;
  • B. B. If statement II is the cause and statement I is its effect;
  • C. C. If both the statements I and II are independent causes;
  • D. D. If both the statements I and II are effects of independent causes;
  • E. E. If both the statements I and II are effects of some common cause;

Explanation: To determine the correct answer, analyze whether the statements have a cause-and-effect relationship or if they occur independently.

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Correct answer: D. If both the statements I and II are effects of independent causes;

90. Directions: Read the following information and give answer.Ghulam Rasool is shorter than Ali but taller than Kamran.Naeem is shorter than Kamran.Jameel is taller than Naeem.Ali is taller than Jameel.Who among them is the tallest?

  • A. Ali
  • B. Naeem
  • C. Kamran
  • D. Jameel

Explanation: Let's analyze the statements:Ghulam Rasool is shorter than Ali but taller than Kamran.Naeem is shorter than Kamran.Jameel is taller than…

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Correct answer: Ali

91. In He-Ne laser, lasing gas is

  • A. He
  • B. Ne
  • C. both He and Ne
  • D. hydrogen

Explanation: C is the right option In a He-Ne laser, the lasing gas is a mixture of helium (He) and neon (Ne).

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Correct answer: both He and Ne

92. To find the shortest wavelength in the Paschen series, the value of n used is

  • A. 2
  • B. 4
  • C. 5
  • D. ∞

Explanation: C is the right option As n decreases in the initial state (higher level), the term 1 / n² in the equation becomes larger, leading to a…

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Correct answer: 5

93. Target material used in an X-ray tube must have the following properties

  • A. high atomic numbers and high melting point
  • B. high atomic numbers and low melting point
  • C. low atomic number and low melting point
  • D. high atomic number only

Explanation: A is the right optionThe target material in an X-ray tube should have high atomic numbers to enhance X-ray production through interactions…

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Correct answer: high atomic numbers and high melting point

94. To ionize a hydrogen atom from its ground state, the energy required is

  • A. 13.6 eV
  • B. -13.6 eV
  • C. +3.4 eV
  • D. -3.4 eV

Explanation: A is the right option The ionization energy required to remove an electron from the ground state of a hydrogen atom is 13.6 electron volts…

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Correct answer: 13.6 eV

95. The underlying principle of laser operation is

  • A. induced absorption
  • B. spontaneous emission
  • C. stimulated emission
  • D. all

Explanation: C is the right option The underlying principle of laser operation is stimulated emission.

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Correct answer: stimulated emission

96. In CAT, the beam of X-rays used is of

  • A. spherical-shaped
  • B. pencil-shaped
  • C. fan-shaped
  • D. circular-shaped

Explanation: C is the right option In computed tomography (CAT or CT), the X-ray beam used is typically fan-shaped.

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Correct answer: fan-shaped

97. Which of the following detectors is suitable for fast counting?

  • A. solid-state detector
  • B. G-M counter
  • C. Wilson cloud chamber
  • D. all are correct

Explanation: B is the right option The Geiger-Muller (G-M) counter is suitable for fast counting of particles due to its ability to detect individual…

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Correct answer: G-M counter

98. In a solid-state detector, the p-n junction is operated under

  • A. forward bias
  • B. reverse bias
  • C. no bias at all
  • D. reverse bias for small energy particles and no bias for large

Explanation: B is the right option In a solid-state detector, the p-n junction is typically operated under reverse bias conditions.

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Correct answer: reverse bias

99. In which of the following detectors, the size of the pulse is independent of the energy of the particle?

  • A. G.M. counter
  • B. Solid-state detector
  • C. Wilson cloud chamber
  • D. none

Explanation: D is the right option Here's why:G.M. counter (Geiger-Müller counter): In a G.M.

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Correct answer: none

100. Hydrogen atoms are excited to the stationary state designated by the principal quantum number n = 4. The maximum number of spectral lines observed is

  • A. 2
  • B. 4
  • C. 3
  • D. 6

Explanation: D is the right option Here's why:: When hydrogen atoms are excited to the n = 4 state, they can transition to lower energy states…

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Correct answer: 6
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