Chapter 6: Structure of Atom — Online MCQ Test
PHYSICAL SCIENCES · CLASS 10th · Telangana State Board
Practice Chapter 6: Structure of Atom with a free chapter-wise online MCQ test.
This chapter covers: Tracing modern atomic theory this chapter explores electron arrangements within atoms beyond early planetary models. Students study electromagnetic radiation Planck's quantum theor....
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Chapter 6: Structure of Atom — Important Questions & Answers
According to Planck's quantum theory, energy is emitted or absorbed in discrete units called ___.
- A. Photons
- B. Quanta
- C. Electrons
- D. Wavelengths
Answer: B. Quanta
Planck proposed that energy is emitted or absorbed in discrete packets called quanta (plural of quantum). The energy of each quantum is given by E = hν.
Planck proposed that energy is emitted or absorbed in discrete packets called quanta (plural of quantum). The energy of each quantum is given by E = hν.
Which of the following is NOT a quantum number used to describe an electron's position in an atom?
- A. Principal quantum number (n)
- B. Angular momentum quantum number (l)
- C. Magnetic quantum number (m_s)
- D. Spin quantum number (m_s)
Answer: C. Magnetic quantum number (m_s)
The magnetic quantum number is represented as m_l (not m_s), which describes the orientation of the orbital. The spin quantum number is correctly m_s. The question uses m_s incorrectly in option C.
The magnetic quantum number is represented as m_l (not m_s), which describes the orientation of the orbital. The spin quantum number is correctly m_s. The question uses m_s incorrectly in option C.
What is the de Broglie wavelength of a particle with momentum p?
- A. λ = hp
- B. λ = h/p
- C. λ = p/h
- D. λ = h²/p
Answer: B. λ = h/p
De Broglie proposed that wavelength λ = h/p, where h is Planck's constant and p is momentum. This equation relates particle properties to wave properties.
De Broglie proposed that wavelength λ = h/p, where h is Planck's constant and p is momentum. This equation relates particle properties to wave properties.
Consider two atoms: Atom A has a single electron in the 3d orbital, and Atom B has a single electron in the 4s orbital. According to the Aufbau principle, which orbital would be filled first during the building of an atom, and why?
- A. 3d fills first because n is smaller
- B. 4s fills first because it has lower energy despite higher n
- C. 3d fills first because d-orbitals are more stable
- D. Both fill simultaneously with equal probability
Answer: B. 4s fills first because it has lower energy despite higher n
The Aufbau principle states that orbitals are filled in order of increasing energy. The 4s orbital fills before 3d because 4s has lower energy (n+l value of 4 for 4s vs 5 for 3d), despite 4s having a higher principal quantum number.
The Aufbau principle states that orbitals are filled in order of increasing energy. The 4s orbital fills before 3d because 4s has lower energy (n+l value of 4 for 4s vs 5 for 3d), despite 4s having a higher principal quantum number.
A student observes that an element's atoms show an unusual electron configuration where one d-orbital electron has promoted to an s-orbital of higher energy. This violates ___.
- A. Heisenberg's uncertainty principle
- B. The Aufbau principle
- C. Hund's rule of maximum multiplicity
- D. The Pauli exclusion principle
Answer: B. The Aufbau principle
The Aufbau principle dictates that electrons fill orbitals in order of increasing energy. Promoting an electron from a lower-energy d-orbital to a higher-energy s-orbital violates this principle, though exceptions exist in some transition metals due to stability considerations.
The Aufbau principle dictates that electrons fill orbitals in order of increasing energy. Promoting an electron from a lower-energy d-orbital to a higher-energy s-orbital violates this principle, though exceptions exist in some transition metals due to stability considerations.