Chapter Exam

Chapter 3: Classification of Elements and Periodicity in Properties — Online MCQ Test

Q: According to the modern periodic law, the properties of elements are periodic functions of their ____.

Answer: B. atomic numbers — Modern periodic law states that the physical and chemical properties of elements are periodic functions of their atomic numbers.

Q: Which of the following is a period in the periodic table?

Answer: B. A horizontal row — A period is a horizontal row in the periodic table.

Q: Across a period, the metallic character generally:

Answer: B. decreases — Metallic character decreases across a period as atoms become less likely to lose electrons.

Q: Which element is expected to have the lowest first ionization enthalpy?

Answer: B. B — Boron has a lower first ionization enthalpy than beryllium because its electron is removed from a higher-energy 2p orbital.

CHEMISTRY · CLASS 11 FIRST PUC · Karnataka State Board

Practice Chapter 3: Classification of Elements and Periodicity in Properties with a free chapter-wise online MCQ test for Karnataka State Board CLASS 11 FIRST PUC CHEMISTRY. This chapter covers: Periodic table Periodic law Atomic radius Ionization enthalpy Electron affinity Electronegativity Metallic character Non metallic character Periodic trends. AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter 3: Classification of Elements and Periodicity in Properties — Important Questions & Answers (FAQ)

Frequently asked questions from Karnataka State Board CLASS 11 FIRST PUC CHEMISTRY — Chapter 3: Classification of Elements and Periodicity in Properties, with answers and explanations. These are sample questions; the exam has its own separate question set.

According to the modern periodic law, the properties of elements are periodic functions of their ____.

A. atomic masses
B. atomic numbers ✓
C. neutron numbers
D. valence electrons only

Answer: B. atomic numbers
Modern periodic law states that the physical and chemical properties of elements are periodic functions of their atomic numbers.

Which of the following is a period in the periodic table?

A. A vertical column
B. A horizontal row ✓
C. A family of elements with same valency
D. A group of transition metals only

Answer: B. A horizontal row
A period is a horizontal row in the periodic table.

Across a period, the metallic character generally:

A. increases
B. decreases ✓
C. remains unchanged
D. first increases then remains constant

Answer: B. decreases
Metallic character decreases across a period as atoms become less likely to lose electrons.

Which element is expected to have the lowest first ionization enthalpy?

A. Be
B. B ✓
C. C
D. N

Answer: B. B
Boron has a lower first ionization enthalpy than beryllium because its electron is removed from a higher-energy 2p orbital.

A student says: 'Fluorine should have a greater electron affinity than chlorine because fluorine is more electronegative.' Which is the best response?

A. The statement is correct; electron affinity always follows electronegativity exactly
B. The statement is incorrect; chlorine has slightly higher electron affinity than fluorine due to less electron-electron repulsion in a larger 3p orbital ✓
C. The statement is incorrect; fluorine cannot gain electrons
D. The statement is correct only in periods, not groups

Answer: B. The statement is incorrect; chlorine has slightly higher electron affinity than fluorine due to less electron-electron repulsion in a larger 3p orbital
Electron affinity and electronegativity are related but not identical. Fluorine's small size increases repulsion when an extra electron is added, so chlorine has slightly higher electron affinity.

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