Searching for important Periodic Classification of Elements Class 10 MCQs for CBSE board preparation? This page is designed for students who want quick practice, concept clarity, and exam-focused revision without wasting time scrolling through lengthy theory. The MCQ sections below cover important concepts from Chapter 5 of Class 10 Science including modern periodic law, Mendeleev periodic table, periodic trends, groups and periods, valency, and atomic size trends.
These objective questions are structured according to the latest CBSE Board and NCERT pattern to help students improve accuracy, strengthen conceptual understanding, and prepare for board-level competency-based questions. Along with MCQ practice, this page also includes quick revision notes, important exam focus areas, and commonly confused concepts that students should revise before exams.
If you are preparing multiple chapters together, you can also explore our complete Class 10 Science MCQs collection for chapter-wise practice. For subject-wise objective question practice across different classes and topics, visit our complete Class 10 MCQs section and the full MCQs for organized revision resources and board exam preparation support.
Practice Periodic Classification of Elements Class 10 MCQs
This chapter includes concept-based questions that frequently appear in CBSE board exams. The MCQs below are structured topic-wise to make revision faster, clearer, and more student-friendly.
The practice sections will include:
- NCERT based MCQs
- Board-level objective questions
- Assertion and reason questions
- Case-based MCQs
- Competency-based questions
- Important conceptual questions
Periodic Classification of Elements Class 10 MCQs with Answers
Practice topic-wise MCQs from Chapter 5 of Class 10 Science based on the latest CBSE and NCERT pattern. This section covers important concepts like modern periodic law, Mendeleev periodic table, periodic trends, groups and periods, assertion-reason questions, and competency-based board exam practice.
Q. Henry Moseley demonstrated that a fundamental property of an element can be used to organize the periodic table more effectively than atomic mass. Identify this property.
A. Total number of nucleons
B. Number of protons in the nucleus
C. Number of neutrons in the core
D. Total number of stable isotopes
Answer: B. Number of protons in the nucleus
Explanation: Moseley discovered that atomic number, which represents the number of protons in the nucleus, is the correct basis for arranging elements in the periodic table.
Q. A student analyzes a highly reactive non-metal located at the top of the halogen group. Which element matches this description?
A. Fluorine
B. Oxygen
C. Chlorine
D. Sodium
Answer: A. Fluorine
Explanation: Fluorine is the most reactive non-metal because of its very small atomic size and high electronegativity.
Q. Consider the elements Nitrogen, Oxygen, and Fluorine, which all belong to the second period. Choose the correct increasing order of atomic size.
A. Nitrogen < Oxygen < Fluorine
B. Fluorine < Oxygen < Nitrogen
C. Oxygen < Nitrogen < Fluorine
D. Fluorine < Nitrogen < Oxygen
Answer: B. Fluorine < Oxygen < Nitrogen
Explanation: Atomic size decreases from left to right across a period because nuclear charge increases.
Q. An unknown element X forms a chloride with the formula XCl2. In which group is X most likely placed?
A. Group 1
B. Group 13
C. Group 2
D. Group 14
Answer: C. Group 2
Explanation: The formula XCl2 shows that X has valency 2, which is characteristic of Group 2 elements.
Q. How does electropositive character change from left to right across Period 3?
A. It steadily decreases
B. It first increases, then decreases
C. It steadily increases
D. It remains unchanged
Answer: A. It steadily decreases
Explanation: Across a period, effective nuclear charge increases, making it harder for atoms to lose electrons.
Q. What is the main characteristic of Group 18 elements?
A. One electron in the outermost shell
B. Completely filled valence shell
C. Formation of diatomic molecules
D. High tendency to form ionic compounds
Answer: B. Completely filled valence shell
Explanation: Noble gases have completely filled outermost shells, making them chemically stable and less reactive.
Q. Groups 3 to 12 in the periodic table are known as:
A. Representative elements
B. Lanthanides
C. Transition elements
D. Main-group non-metals
Answer: C. Transition elements
Explanation: These elements have partially filled d-orbitals and are called transition elements.
Q. An element M has electronic configuration 2, 8, 4. Identify its group.
A. Group 4
B. Group 14
C. Group 2
D. Group 12
Answer: B. Group 14
Explanation: The element has 4 valence electrons. For p-block elements, group number = valence electrons + 10. Therefore, 4 + 10 = 14.
Q. Which element has exactly two completely filled energy levels?
A. Helium
B. Argon
C. Neon
D. Krypton
Answer: C. Neon
Explanation: Neon has electronic configuration 2, 8, with both shells completely filled.
Q. What was one major success of Mendeleev’s periodic table?
A. Prediction of properties of undiscovered elements
B. Prediction that no elements exist after Uranium
C. Calculation of radioactive decay rates
D. Prediction that all missing elements are noble gases
Answer: A. Prediction of properties of undiscovered elements
Explanation: Mendeleev predicted properties of undiscovered elements such as Gallium and Germanium.
Q. What trend is observed in atomic radius from Sodium to Chlorine?
A. Atomic radius increases
B. Atomic radius decreases
C. Atomic radius remains constant
D. Atomic radius changes irregularly
Answer: B. Atomic radius decreases
Explanation: Increasing nuclear charge across the period pulls electrons closer to the nucleus.
Q. How does Boron generally achieve stability?
A. By losing 3 electrons
B. By sharing 3 electrons
C. By gaining 5 electrons
D. By forming metallic bonds only
Answer: B. By sharing 3 electrons
Explanation: Boron mainly forms covalent compounds by sharing electrons.
Q. How does electronegativity change from left to right across a period?
A. It decreases
B. It increases
C. It remains constant
D. It fluctuates randomly
Answer: B. It increases
Explanation: Atomic size decreases and nuclear attraction increases across a period.
Q. Why does metallic character increase down Group 1?
A. Nuclear charge decreases
B. Valence electrons move farther from the nucleus
C. Number of valence electrons changes
D. Atomic size decreases
Answer: B. Valence electrons move farther from the nucleus
Explanation: Increased shielding and atomic size make electron loss easier.
Q. How does valency vary across the second period?
A. It increases from 1 to 8
B. It decreases from 7 to 1
C. It increases from 1 to 4, then decreases to 0
D. It remains 2 throughout
Answer: C. It increases from 1 to 4, then decreases to 0
Explanation: Valency first increases up to Group 14, then decreases toward noble gases.
Q. The 14 elements following Actinium are called:
A. Lanthanides
B. Transition metals
C. Actinides
D. Chalcogens
Answer: C. Actinides
Explanation: These are f-block elements in which the 5f orbitals are progressively filled.
Q. An element with atomic number 15 will show properties similar to:
A. Beryllium
B. Neon
C. Nitrogen
D. Oxygen
Answer: C. Nitrogen
Explanation: Both elements have 5 valence electrons and belong to the same group.
Q. An element with atomic number 8 belongs to:
A. Group 6, Period 2
B. Group 16, Period 2
C. Group 16, Period 4
D. Group 8, Period 2
Answer: B. Group 16, Period 2
Explanation: Oxygen has electronic configuration 2, 6, so it belongs to Group 16 and Period 2.
Q. An element in Group 2 and Period 2 has how many valence electrons?
A. 2
B. 4
C. 1
D. 8
Answer: A. 2
Explanation: Group 2 elements contain 2 electrons in their outermost shell.
Q. Which element in Period 3 has the smallest atomic volume excluding noble gases?
A. Sodium
B. Silicon
C. Chlorine
D. Argon
Answer: C. Chlorine
Explanation: Chlorine experiences the highest effective nuclear charge among non-noble gas elements in Period 3.
Q. What is the electronic configuration of Al3+?
A. 2, 8, 3
B. 2, 8
C. 2, 8, 8
D. 2, 4
Answer: B. 2, 8
Explanation: Aluminium loses 3 electrons to form Al3+, leaving a stable configuration of 2, 8.
Q. Which set is NOT a Dobereiner Triad?
A. Lithium, Sodium, Potassium
B. Calcium, Strontium, Barium
C. Chlorine, Bromine, Iodine
D. Beryllium, Magnesium, Chromium
Answer: D. Beryllium, Magnesium, Chromium
Explanation: These elements neither belong to the same group nor follow the triad relationship.
Q. Which statement about noble gases is correct?
A. They are radioactive liquids
B. They exist as monoatomic gases
C. They form strong ionic bonds easily
D. They have very low ionization energy
Answer: B. They exist as monoatomic gases
Explanation: Noble gases have stable electronic configurations and exist independently as single atoms.
Q. Which sequence represents an incorrect vertical group arrangement?
A. Nitrogen, Phosphorus, Arsenic
B. Copper, Silver, Gold
C. Calcium, Bromine, Barium
D. Chlorine, Bromine, Iodine
Answer: C. Calcium, Bromine, Barium
Explanation: Calcium and Barium belong to Group 2, whereas Bromine belongs to Group 17.
Q. An element forms an oxide that turns red litmus blue. What is a likely atomic number of the element?
A. 7
B. 17
C. 11
D. 14
Answer: C. 11
Explanation: Sodium (atomic number 11) forms sodium oxide (Na2O), which is basic in nature.
Q. An element has electronic configuration 1s2 2s2 2p6 3s1. Which statement is incorrect?
A. It reacts with water to form a hydroxide
B. It behaves as a non-metal with high electron affinity
C. It has valency 1
D. It forms a univalent positive ion
Answer: B. It behaves as a non-metal with high electron affinity
Explanation: The configuration belongs to Sodium, which is a highly reactive metal.
Q. Which groups contain s-block elements?
A. Groups 13 and 14
B. Groups 1 and 2
C. Groups 15 and 16
D. Groups 17 and 18
Answer: B. Groups 1 and 2
Explanation: s-block elements have valence electrons in the s-orbital.
Q. An element has electronic configuration 1s2 2s2 2p6 3s2 3p4. Identify its group.
A. Group 4
B. Group 6
C. Group 16
D. Group 14
Answer: C. Group 16
Explanation: The element has 6 valence electrons, so its group number is 16.
Q. Which ion has the smallest ionic radius?
A. Na+
B. Mg2+
C. Al3+
D. K+
Answer: C. Al3+
Explanation: Al3+ has the highest nuclear charge among these ions, pulling electrons closer to the nucleus.
Q. Up to which element was Newlands’ Law of Octaves applicable?
A. Oxygen
B. Potassium
C. Calcium
D. Cobalt
Answer: C. Calcium
Explanation: Newlands’ Law of Octaves worked correctly only up to Calcium.
Quick Chapter Overview
The chapter Periodic Classification of Elements explains how scientists arranged elements based on similarities in their properties. Students learn about Dobereiner Triads, Newlands Law of Octaves, Mendeleev’s periodic table, the modern periodic law, and periodic trends like atomic size, valency, and metallic character.
This chapter is important because many board exam questions are directly based on trends and concept application.
What You’ll Practice in These MCQs
| Topic | Focus Area |
|---|---|
| Dobereiner Triads | Early element classification |
| Newlands Law of Octaves | Repetition of properties |
| Mendeleev Periodic Table | Arrangement by atomic mass |
| Modern Periodic Table | Atomic number based classification |
| Groups and Periods | Element positioning |
| Periodic Trends | Atomic size and metallic character |
| Valency | Variation across periods |
| Noble Gases | Stable electronic configuration |
Quick Revision Notes
Modern Periodic Law
The properties of elements are periodic functions of their atomic numbers.
Groups and Periods
Groups are vertical columns while periods are horizontal rows in the periodic table.
Atomic Size Trend
Atomic size decreases across a period and increases down a group.
Metallic Character Trend
Metallic character decreases across a period and increases down a group.
Mendeleev Periodic Table
Mendeleev arranged elements according to atomic mass and left gaps for undiscovered elements.
Important Exam Focus Areas
Students should focus more on:
- modern periodic law
- atomic number based classification
- trends in atomic size
- metallic and non-metallic character
- valency trends
- Mendeleev achievements and limitations
- difference between groups and periods
These concepts are commonly asked in MCQs, assertion-reason, and competency-based questions.
Tips to Solve MCQs Faster
- Understand trends instead of memorizing complete tables.
- Learn the difference between groups and periods clearly.
- Focus on atomic number based logic.
- Revise NCERT examples carefully.
- Practice assertion-reason questions regularly.
Common Mistakes Students Make
| Common Mistake | Better Approach |
|---|---|
| Confusing atomic mass and atomic number | Focus on modern periodic law |
| Mixing groups and periods | Remember vertical and horizontal arrangement |
| Memorizing trends without understanding | Learn concept logic properly |
| Ignoring NCERT examples | Practice NCERT-based applications |
Conclusion
Periodic Classification of Elements is one of the most scoring chapters in Class 10 Science when concepts are understood properly. Regular MCQ practice, quick revision, and strong understanding of periodic trends can help students solve board-level questions with better speed and accuracy.
