intro
MCQs 1:
What would be the maximum number of spectral lines produced when an electron transitions from the 5th to the 3rd orbit?
Topic: Quantum Mechanics and Spectral Lines
Correct Answer: D) Three
- The maximum number of spectral lines can be calculated using the formula (n-p)(n-p+1)/2, where 'n' represents the initial orbit and 'p' the final orbit.
- Here, the electron jumps from the 5th orbit (n = 5) to the 3rd orbit (p = 3).
- Substituting these values into the formula, we get (5-3)(5-3+1)/2 = 3.
- Therefore, the correct answer is D) Three.
MCQs 2:
Within the hydrogen spectrum, which series is located in the ultraviolet region and is associated with the transition producing the smallest wavelength?
Topic: Hydrogen Spectrum and Wavelength
Correct Answer: C) Lyman series
- The question asks for the series in the hydrogen spectrum that lies in the ultraviolet region and corresponds to the transition with the minimum wavelength.
- The Lyman series fits this description, as it falls within the ultraviolet region.
- Hence, the correct answer is C) Lyman series.
MCQs 3:
Which of the following series exhibits the greatest frequency?
Topic: Spectrum Series and Frequency
Correct Answer: A) Lyman series
- Frequency and wavelength are inversely proportional - as wavelength decreases, frequency increases.
- The Lyman series has the shortest wavelength, and therefore, by the relationship mentioned above, it has the highest frequency.
- Hence, the correct answer is A) Lyman series.
MCQs 4:
In which region does the Paschen series reside?
Topic: Spectrum Series and Wavelength Regions
Correct Answer: C) Infrared region
- The question is asking for the region in which the Paschen series of the hydrogen spectrum is located.
- The Paschen series is found in the infrared region.
- Hence, the correct answer is C) Infrared region.
MCQs 5:
In a hydrogen atom, an electron will emit radiation with the shortest wavelength during a transition from:
Topic: Hydrogen Atom and Emitted Radiation
Correct Answer: A) 2nd orbit to 1st orbit
- The wavelength of radiation emitted by an electron in a hydrogen atom is determined by the energy difference between the orbits.
- The greatest energy (and thus the shortest wavelength) is released when an electron transitions from the 2nd orbit to the 1st orbit.
- Hence, the correct answer is A) 2nd orbit to 1st orbit.
MCQs 6:
Which of the following demonstrates a characteristic line spectrum?
Topic: Line Spectrum Characteristics
Correct Answer: B) Atoms
- A line spectrum, which refers to the distinct light bands produced when the light emitted by a particular substance passes through a prism, is a characteristic feature of atoms subjected to a magnetic field.
- Hence, the correct answer is B) Atoms.
MCQs 7:
Which spectral series emits radiations that are more energetic than those of the others?
Topic: Energetic Radiations and Spectral Series
Correct Answer: A) Lyman series
- Energy of radiations corresponds to their place in the electromagnetic spectrum. The more towards the UV region the series lies, the more energetic the radiation.
- The Lyman series lies in the ultraviolet region, which is associated with high-energy radiation.
- Hence, the correct answer is A) Lyman series.
Question 8:
Which of the following has the highest degree of coherence?
Topic: Coherence in Light Sources
Correct Answer: D) Laser
- The question is asking about the light source with the highest degree of coherence.
- Coherence refers to the property of waves that enables them to maintain a constant phase relationship.
- Lasers are known for producing light that is highly coherent.
- Therefore, the correct answer is D) Laser.
Question 9:
What is the duration of the metastable state for an atom in laser illumination?
Topic: Metastable State in Laser Illumination
Correct Answer: C) 10^-3 sec
- The question is asking about the duration of the metastable state for an atom in laser illumination.
- A metastable state is an excited state with a longer lifespan than usual.
- The duration of the metastable state for an atom in laser illumination is 10^-3 seconds.
- This duration is longer than the typical excited state.
- Hence, the correct answer is C) 10^-3 sec.
Question 10:
The Bracket series corresponds to all transitions of an electron that terminate on which orbit?
Topic: Bracket Series and Electron Transitions
Correct Answer: B) 4th orbit
- The question is about the Bracket series, which is associated with electron transitions in an atom.
- The Bracket series is characterized by all transitions that terminate on the 4th orbit.
- Therefore, the correct answer is B) 4th orbit.
Question 11:
Which series corresponds to a wave number of RH/9?
Topic: Correspondence Between Wave Numbers and Series
Correct Answer: C) Paschen series
- This question deals with the relationship between wave numbers and spectral series in the context of atomic physics.
- The given wave number, denoted by RH/9, aligns with the Paschen series.
- As a result, the correct response is C) Paschen series.
Question 12:
Which spectral series corresponds to a wave number represented by RH/9?
Topic: Wave Numbers and Their Series Associations
Correct Answer: C) Paschen series
- This question revisits the concept of wave numbers and how they relate to specific spectral series.
- Again, a wave number represented by RH/9 is linked to the Paschen series.
- Consequently, the correct option is C) Paschen series.
Question 13:
What is the ratio of the longest wavelengths associated with the Lyman and Balmer series in the hydrogen spectrum?
Topic: Wavelength Ratios in the Hydrogen Spectrum
Correct Answer: C) 5/27
- The question pertains to the hydrogen spectrum, specifically the ratio of the longest wavelengths within the Lyman and Balmer series.
- The ratio of these longest wavelengths is represented by 5/27.
- Therefore, the correct answer is C) 5/27.
Question 14:
Which series is associated with the lowest wavelength transition in Hydrogen atoms?
Topic: Wavelength Transitions in Hydrogen Atoms
Correct Answer: B) Lyman Series
- The question is asking about the series that corresponds to the smallest wavelength transition in Hydrogen atoms.
- The Lyman series is known for corresponding to the highest energy transition, which results in the shortest wavelength, i.e., the n→1 transition.
- Hence, the correct answer is B) Lyman Series.
Question 15:
What is the ratio between kinetic energy and total energy of an electron in a hydrogen atom?
Topic: Energy Ratios in a Hydrogen Atom
Correct Answer: B) 1 : -1
- The question focuses on the relationship between the kinetic energy and the total energy of an electron within a hydrogen atom.
- By comparing the final formulas of total energy and kinetic energy, it can be seen that their ratio is 1 : -1.
- Therefore, the correct answer is B) 1 : -1.
Question 16:
Which Bohr's Model Postulate of the hydrogen atom conflicts with classical physics principles?
Topic: Conflict of Bohr's Model Postulates with Classical Physics
Correct Answer: A) 1st
- This question is about identifying which postulate of Bohr’s Model for the hydrogen atom contradicts with classical physics principles.
- It's the first postulate of Bohr's Model that conflicts with classical physics.
- As a result, the correct answer is A) 1st.
Question 17:
What would a mono-atomic gas display upon ionization?
Topic: Ionization Spectra of Mono-Atomic Gases
Correct Answer: A) Line spectrum
- The question revolves around the spectra characteristic shown by a mono-atomic gas when it undergoes ionization.
- In general, atoms tend to exhibit a line spectrum, while molecules show a band spectrum and a black body emits a continuous spectrum.
- Thus, the correct answer is A) Line spectrum.
Question 18:
Which property remains constant for three spectral series in the infrared region?
Topic: Inherent Properties of Infrared Spectral Series
Correct Answer: C) Velocity
- This question seeks to understand which of the given properties - frequency, wavelength, or velocity - holds the same value across three spectral series in the infrared region.
- It should be noted that the velocity is a universal constant for all electromagnetic waves, equalling the speed of light.
- Therefore, the correct answer is C) Velocity.
Question 19:
Given that the half-life of radium is approximately 1600 years, how much radium would remain after 6400 years from an initial quantity of radium?
Topic: Half-Life of Radium
Correct Answer: C) 62 mg
- This question pertains to the concept of half-life, specifically of radium, and how much of it would remain after a given duration.
- The half-life of radium is about 1600 years. Therefore, after 6400 years, which is four half-life periods, the remaining quantity of radium would be 1/16 of the initial amount.
- As such, the correct answer is C) 62 mg.
Question 20:
In a hydrogen atom, where are electrons primarily positioned?
Topic: Electron States in a Hydrogen Atom
Correct Answer: A) Ground state
- The question is asking about the common position of electrons in a hydrogen atom.
- Normally, electrons in any atom reside in the ground state which is the state of lowest energy.
- Therefore, the correct answer is A) Ground state.
Question 21:
For the Balmer series, the series limit represents an electron transition m → n. What is the pair (m, n)?
Topic: Balmer Series Electron Transitions
Correct Answer: D) (∞, 2)
- This question concerns the electron transitions that define the series limit for the Balmer series.
- For the Balmer series, an electron should leap from any higher energy level to the second energy level. Hence, the pair (m, n) is (∞, 2).
- Consequently, the correct answer is D) (∞, 2).
MCQ 22:
How many series exist in the hydrogen spectrum?
Topic: Spectral Series in a Hydrogen Atom
Correct Answer: B) Five
- The hydrogen spectrum consists of five series: the Lyman series (ultraviolet region), the Balmer series (visible region), the Paschen series (infrared region), the Brackett series (infrared region), and the Pfund series (infrared region).
- Hence, the correct answer is B) Five.
MCQ 23:
What is the formula for the Pfund series in the hydrogen spectrum?
Topic: The Pfund Series Formula
Correct Answer: A) 1/λ = RH(1/52 - 1/n²)
- The Pfund series, which falls within the infrared region, has the formula 1/λ = RH(1/52 - 1/n²), which can be seen in option A.
- Thus, the correct answer is A) 1/λ = RH(1/52 - 1/n²).
MCQ 24:
What are potential applications of a laser beam?
Topic: Uses of a Laser Beam
Correct Answer: D) All the above-mentioned uses.
- Applications of a laser beam include welding detached retinas, destroying tissues in a specific area, and sealing off capillaries to prevent diseases, as stated in option D.
- Therefore, the correct answer is D) All the above-mentioned uses.
MCQ 25:
Which spectral series in the hydrogen spectrum has the highest frequency?
Topic: Spectral Series Frequencies in a Hydrogen Atom
Correct Answer: A) Lyman series
- The Lyman series has the shortest wavelength, and since frequency (f) is inversely proportional to wavelength (λ) given a constant velocity (v), it has the highest frequency.
- Hence, the correct answer is A) Lyman series.
MCQ 26:
A hydrogen atom in its ground state is subjected to a homogenous radiation of wavelength λ = 975Å. How many spectral lines will be emitted in the resulting spectrum?
Topic: Spectral Lines from Excited Hydrogen Atom
Correct Answer: A) Six
- The spectral line count can be calculated using the formula n(n-1)/2 where n is the energy level the electron is excited to. For a wavelength of λ = 975Å, the electron is excited to the n=4 energy level.
- Therefore, the correct answer is A) Six.
MCQ 27:
Why doesn't a hydrogen atom emit X-ray radiation?
Topic: Emission Spectrum of a Hydrogen Atom
Correct Answer: A) The energy levels are closely spaced.
- The energy levels in a hydrogen atom are closely spaced, leading to the emission of high-energy radiations with short wavelengths during electron transitions. Even the shortest distance, i.e., the Lyman series, results in wavelengths in the ultraviolet region. X-ray photons are long radiation, which is why hydrogen atoms do not emit X-rays.
- Thus, the correct answer is A) The energy levels are closely spaced.
MCQ 28:
In which part of the spectrum do the prominent lines of the Balmer series appear?
Topic: Balmer Series in the Light Spectrum
Correct Answer: A) Visible
- The Balmer series specifically falls within the visible light region of the light spectrum.
- Consequently, the correct answer is A) Visible.
Question 29:
What is the typical composition ratio of Helium (He) to Neon (Ne) in a common gas laser?
Topic: Composition of a He-Ne Gas Laser
Correct Answer: B) 85% Helium, 15% Neon
- This question probes the standard proportioning of Helium and Neon in a He-Ne gas laser.
- A customary He-Ne gas laser typically contains 85% Helium and 15% Neon.
- Thus, the correct answer is B) 85% Helium, 15% Neon.
Question 30:
In the electromagnetic spectrum, in what region does the Pfund series of the atomic hydrogen spectrum lie?
Topic: Pfund Series in the Electromagnetic Spectrum
Correct Answer: C) Infrared
- The question requires the identification of the region in the electromagnetic spectrum where the Pfund series of the atomic hydrogen spectrum is found.
- The Pfund series of the atomic hydrogen spectrum lies in the infrared region.
- Hence, the correct answer is C) Infrared.
Question 31:
What type of spectrum is produced from a hydrogen-filled discharge tube?
Topic: Spectral Emission from a Hydrogen-Filled Discharge Tube
Correct Answer: C) Line spectrum
- The question is about determining the type of spectrum emitted from a hydrogen-filled discharge tube.
- The emission from a hydrogen-filled discharge tube exhibits a line spectrum, which consists of distinct lines corresponding to single wavelengths or frequencies of emitted or absorbed radiation.
- Therefore, the correct answer is C) Line spectrum.
Question 32:
How long does it take for excited atoms to return to their ground state?
Topic: Relaxation Time of Excited Atoms
Correct Answer: B) 10^-8 s
- The question is asking to determine the typical time it takes for excited atoms to return to their ground state, also known as relaxation time.
- The relaxation time of excited atoms is usually in the order of 10^-8 seconds.
- Therefore, the correct answer is B) 10^-8 s.