intro
MCQs 1:
What is the correct sequence of characteristics represented by quantum numbers?
Topic: Quantum Numbers and Their Characteristics
Correct Answer: A) Size, Shape, Orientation
- The quantum numbers represent certain characteristics of electron properties in an atom, listed in a specific order.
- The sequence is typically stated as Size (principal quantum number, n), Shape (azimuthal quantum number, l), and Orientation (magnetic quantum number, m).
- Therefore, the correct sequence among the given options is A) "Size, Shape, Orientation".
MCQs 2:
What is the maximum number of electrons that the 4f orbitals can accommodate?
Topic: Electron Capacity of Orbitals
Correct Answer: D) 14
- The 4f orbitals have seven degenerate orbitals.
- Each degenerate orbital can accommodate a maximum of 2 electrons.
- So, the total number of electrons that can be held in seven degenerate orbitals is 14, making option D) "14" the correct answer.
MCQs 3:
Which rule or principle dictates that two electrons in an atomic orbital must have opposite spin?
Topic: Electron Spin and Atomic Principles
Correct Answer: B) Pauli’s Exclusion Principle
- The Pauli’s Exclusion Principle states that it's impossible for two electrons in the same atomic orbital to have identical sets of quantum numbers.
- In other words, electrons in the same atomic orbital must have opposite spins.
- Therefore, option B) "Pauli’s Exclusion Principle" is the correct answer.
MCQs 4:
Arrange the energy levels of 4s, 4p, and 3d orbitals in ascending order:
Topic: Energy Levels of Orbitals
Correct Answer: B) 4s < 3d < 4p
- The energy levels of orbitals play a crucial role in the determination of an electron's location within the atom.
- The correct order is 4s < 3d < 4p.
- Thus, option B) "4s < 3d < 4p" is the correct answer.
MCQs 5:
The electron's charge-to-mass ratio, e/m, is known to be 1.7586 x 10^11 Coulombs kg^-1. Can you determine the electron's mass?
Topic: Electron's Mass Calculation
Correct Answer: A) 9.1095 x 10^-31 kg
- The relationship between the electron's charge (e) and mass (m) is given by the equation e/m.
- By transposing this equation, we can find the mass of an electron as m = e / (1.7586 x 10^11 kg^-1).
- Substituting the given value of the electron's charge (1.6022 x 10^-19), the mass of the electron equals 9.1095 x 10^-31 kg.
- So, the correct choice is A) "9.1095 x 10^-31 kg".
MCQs 6:
Which principle explains why two electrons occupying the same atomic orbital must demonstrate antiparallel spins?
Topic: Principle Governing Electron Spin
Correct Answer: C) Pauli's Exclusion Principle
- Electrons occupying the same atomic orbital have unique sets of quantum numbers in accordance with a specific principle.
- This principle, known as Pauli's Exclusion Principle, mandates that two electrons in the same orbital have opposing spins.
- Therefore, the correct answer is C) "Pauli's Exclusion Principle".
MCQs 7:
Which quantum number is responsible for defining the number of orbitals in a given sub-shell?
Topic: Quantum Numbers and Sub-Shell Orbitals
Correct Answer: B) Magnetic quantum number
- The magnetic quantum number "m" provides information about the spatial orientation of orbitals within a sub-shell.
- The various values of 'm' represent the total number of spatially distinct orientations for a sub-shell.
- Thus, the correct answer is B) "Magnetic quantum number".
MCQ 8:
Which type of subshell has the capability to contain up to 10 electrons?
Topic: Electron Capacity of Subshells
Correct Answer: C) d-subshell
- The equation to calculate the number of electrons that a subshell can accommodate is 2(2l+1), where 'l' denotes the azimuthal quantum number.
- For a d-subshell, the value of 'l' is 2.
- Therefore, the total number of electrons in a d-subshell equals 2(2*2+1) = 10 electrons.
- So, the correct choice is C) "d-subshell".
MCQ 9:
What is the relationship between the azimuthal quantum number (l) and the magnetic quantum number (m)?
Topic: Relationship between Quantum Numbers
Correct Answer: C) m = (2l + 1)
- The magnetic quantum number (m) is derived from the azimuthal quantum number (l) using the equation m = (2l + 1).
- For instance, if we take l = 2, the value of m using the given equation becomes 2(2) +1 = 4+ 1 = 5.
- Thus, the correct answer is C) "m = (2l + 1)".
MCQ 10:
Which quantum number helps to describe the size of an electron shell?
Topic: Quantum Numbers and Electron Shell Size
Correct Answer: A) Principle quantum number
- The size of an electron shell is determined by the "n" value in the Schrödinger wave equation.
- The higher the "n" value, the larger the orbit's size.
- Hence, the correct answer is A) "Principle quantum number".
MCQ 11:
What formula is typically used to calculate the number of electrons in a specific sub-shell?
Topic: Electron Count in Sub-Shells
Correct Answer: C) 2 (2l + 1)
- To find the total number of electrons in a certain sub-shell, one typically uses the formula 2 (2l + 1), where 'l' represents the azimuthal quantum number.
- This formula effectively calculates the maximum electron capacity of a sub-shell.
- Therefore, the accurate answer is C) "2 (2l + 1)".
MCQ 12:
By what factor is a proton heavier than an electron?
Topic: Proton-Electron Mass Ratio
Correct Answer: C) 1840 times
- The relative mass of a proton is considerably larger than that of an electron.
- Scientific observations and measurements have shown that a proton is approximately 1840 times heavier than an electron.
- Thus, the correct response is C) "1840 times".
MCQ 13:
What happens to an electron when it revolves in a stationary orbit?
Topic: Electron Behavior in Stationary Orbits
Correct Answer: D) Its energy remains constant
- When an electron revolves in a stationary orbit, its energy state remains steady.
- The electron does not absorb, emit energy, or gain kinetic energy in this stationary state.
- Consequently, the accurate answer is D) "Its energy remains constant".
MCQ 14:
What formula can be used to calculate the total number of orbitals given the magnetic quantum number?
Topic: Orbitals and Magnetic Quantum Numbers
Correct Answer: D) 2l + 1
- The number of orbitals can be determined by the magnetic quantum number via the formula 2l + 1.
- For a given 'l', the total values of 'm' (magnetic quantum number) will be derived from this formula.
- Thus, the correct answer is D) "2l + 1".
Question 15:
What is the total count of orbitals in the energy level n=4?
Topic: Orbital Count in Energy Levels
Correct Answer: C) 16
- The total amount of orbitals in an energy level can be calculated using the formula n².
- Applying this formula for the fourth energy level (n = 4), we get n² = 4² = 16 orbitals.
- Therefore, the accurate answer is C) "16".
Question 16:
What factor influences the characteristics of positive rays?
Topic: Positive Rays Characteristics
Correct Answer: C) The kind of gas in the discharge tube
- The e/m ratio of particles in anode rays is dependent on the type of gas present in the discharge tube.
- As the nature of the gas (mass) changes, this affects the e/m value.
- Hence, the correct choice is C) "The kind of gas in the discharge tube".
Question 17:
What term is used to denote the minimum energy required to expel an electron from an atom's outermost shell?
Topic: Ionization Energy
Correct Answer: C) Energy of Ionization
- The minimum energy necessary to dislodge an electron from the most distant shell of an atom is referred to as Ionization Energy.
- It is not related to Kinetic Energy, Potential Energy, or Electron Tendency.
- Therefore, the correct answer is C) "Energy of Ionization".
Question 18:
Which pair has an electronic configuration similar to neon (Ne-10)?
Topic: Electronic Configuration
Correct Answer: D) Sodium ion (Na+) and Fluoride ion (F–)
- The ions Sodium (Na+) and Fluoride (F–) share the same electronic configuration as Neon.
- This configuration is not the same for the other ion pairs, making D the correct option.
- Thus, the right answer is D) "Sodium ion (Na+) and Fluoride ion (F–)".
Question 19:
What is the numerical value of Rydberg's constant?
Topic: Rydberg's Constant
Correct Answer: C) 1.09678 × 10^7 m^-1
- Rydberg's constant, a fundamental constant in atomic physics, has a value of 1.09678 × 10^7 m^-1.
- The other listed values do not represent the value of Rydberg’s constant.
- Consequently, the correct response is C) "1.09678 × 10^7 m^-1".
Question 20:
Which of the following options correctly represents the maximum occupancy of an atomic orbital?
Topic: Atomic Orbital Occupancy
Correct Answer: B) Three electrons
- An atomic orbital refers to the spatial region where there's a 95% probability of finding an electron.
- According to Pauli's Exclusion Principle, an atomic orbital can house a maximum of two electrons, each with opposing spins.
- It is impossible for three electrons to reside within the same atomic orbital.
- Thus, the correct answer is B) "Three electrons".
Question 21:
If an element has an atomic number of 17, how many orbits will it have?
Topic: Atomic Number and Orbits
Correct Answer: C) Three orbits
- The atomic number of an element signifies the count of protons it possesses.
- Since the atomic number equals the count of electrons in an atom, an atomic number of 17 implies 17 electrons.
- These electrons organize into three different orbits.
- Therefore, the correct answer is C) "Three orbits".
Question 22:
What is the value of (n + l) for a 5f orbital?
Topic: Orbital Quantum Number
Correct Answer: D) Eight
- In this context, 'n' is the primary quantum number and it always equals the digit in consideration, which in this case is 5.
- The azimuthal quantum number (l) for an 'f' orbital is 3.
- By adding these two numbers (n + l), you get a total of 8.
- Hence, the correct answer is D) "Eight".
Question 23:
What happens to the energy of an electron when it revolves in a stationary orbit?
Topic: Electron Energy in Stationary Orbit
Correct Answer: D) The energy of the electron remains unchanged
- The energy of an electron is modified only when it migrates to a different orbit.
- However, when it remains in a stationary orbit, its energy stays constant.
- This implies that there are no changes in energy while an electron revolves in a stationary orbit.
- Thus, the correct response is D) "The energy of the electron remains unchanged".
Question 24:
What is the correct electron configuration of copper, considering that the atomic number of Cu is 29?
Topic: Electron Configuration of Copper
Correct Answer: B) [Ar] 3d10, 4s1
- The 3d-series, namely Chromium (Cr) and Copper (Cu), exhibit an exceptional electronic configuration.
- The general configuration for Chromium should be (Ar) 3d4, 4s2. However, because the 3d-sub shell is close to being half-filled, the 3d orbital receives an electron from 4s and changes its configuration to (Ar) 3d5, 4s1.
- Consequently, the correct answer is B) "[Ar] 3d10, 4s1".
Question 25:
What does the magnetic quantum number describe?
Topic: Magnetic Quantum Number
Correct Answer: A) The orientation of orbitals in a magnetic field
- The magnetic quantum number is a critical concept in quantum mechanics.
- Its primary function is to depict the orientation of orbitals in a magnetic field.
- Therefore, the correct answer is A) "The orientation of orbitals in a magnetic field".
Question 26:
What determines the energy of electrons within a specific orbital in multi-electron atoms?
Topic: Electron Energy in Multi-Electron Atoms
Correct Answer: C) n + l
- The energy of electrons in a specific orbital within multi-electron atoms adheres to the 'n + l' rule.
- This rule aligns with the Aufbau principle, which suggests that electrons occupy energy sub-shells in order of rising energy values.
- For instance, the 'n + l' rule demonstrates that the energy of a 4s sub-shell is lower than that of 3d; hence, the 4s sub-shell fills before the 3d sub-shell.
- So, the correct answer is C) "n + l".
Question 27:
How can one calculate the total number of electrons in a sub-shell?
Topic: Sub-Shell Electron Count
Correct Answer: C) 2(2l + 1)
- The 'l' value determines subshells.
- To calculate the total number of electrons within a sub-shell, one utilizes the formula '2(2l + 1)'.
- This equation allows us to ascertain the electron count within each sub-shell.
- Therefore, the correct answer is C) "2(2l + 1)".
Question 28:
How many quantum numbers are derived from the Schrodinger wave equation when applied to a hydrogen atom?
Topic: Quantum Numbers from the Schrodinger Wave Equation
Correct Answer: B) Three
- The Schrodinger wave equation, when solved for a hydrogen atom, gives us three out of the four quantum numbers.
- These include the Principal quantum number, the Azimuthal quantum number, and the Magnetic quantum number.
- Thus, the correct response is B) "Three".
Question 29:
What is the minimum principal quantum number an electron can possess?
Topic: Minimum Principal Quantum Number
Correct Answer: C) 1
- The principal quantum number is symbolized by 'n'.
- The potential values it can take are 1, 2, 3, 4, 5, 6, 7, clearly indicating that it cannot be zero.
- Therefore, the least principal quantum number an electron can possess is C) "1".
Question 30:
Why does nitrogen have three unpaired electrons?
Topic: Unpaired Electrons in Nitrogen
Correct Answer: D) Hund's rule
- The presence of three unpaired electrons in a nitrogen atom can be justified using Hund's rule.
- According to this rule, electron pairing in any orbital (s, p, d, or f) can't occur until each orbital of the same sublevel contains one electron.
- The electron configuration of Nitrogen is 1s2, 2s2, 2p3.
- 2p orbital has 3 sub-levels, each of which will contain one electron. Pairing will only take place if a fourth electron is added.
- Thus, the correct answer is D) "Hund's rule".