Chapter Exam

Chapter 6: Structure of Atom — Online MCQ Test

Q: According to Planck's quantum theory, energy is emitted or absorbed in discrete units called ___.

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.

Q: Which of the following is NOT a quantum number used to describe an electron's position in an atom?

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.

Q: What is the de Broglie wavelength of a particle with momentum 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.

Q: 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 ___.

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.

PHYSICAL SCIENCES · CLASS 10th · Telangana State Board

Practice Chapter 6: Structure of Atom with a free chapter-wise online MCQ test for Telangana State Board CLASS 10th PHYSICAL SCIENCES. 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.... AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter 6: Structure of Atom — Important Questions & Answers (FAQ)

Frequently asked questions from Telangana State Board CLASS 10th PHYSICAL SCIENCES — Chapter 6: Structure of Atom, with answers and explanations. These are sample questions; the exam has its own separate question set.

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.

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.

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.

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.

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.

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