Periodic Classification of Elements Class 10 MCQs
Periodic Classification of Elements – Class 10 MCQs
Class: 10 |
Subject: Science |
Section: Chemistry |
Topic: Periodic Classification of Elements
Board: CBSE Board Examination
Board: CBSE Board Examination
Instructions: These Multiple Choice Questions (MCQs) are designed strictly as per the NCERT syllabus, making them ideal for CBSE Class 10 Science Board Exams. Each question includes a detailed explanation for better concept clarity.
1. Who proposed the Modern Periodic Law?
Answer: B. Moseley
Explanation: Henry Moseley proposed that the properties of elements are periodic functions of their atomic numbers, not atomic masses. This corrected Mendeleev’s periodic table anomalies.
Explanation: Henry Moseley proposed that the properties of elements are periodic functions of their atomic numbers, not atomic masses. This corrected Mendeleev’s periodic table anomalies.
2. Modern periodic table is based on:
Answer: B. Atomic number
Explanation: Atomic number determines electronic configuration, which governs chemical properties. Hence modern classification uses atomic number.
Explanation: Atomic number determines electronic configuration, which governs chemical properties. Hence modern classification uses atomic number.
3. Number of periods in the modern periodic table:
Answer: B. 7
Explanation: Horizontal rows are called periods. There are 7 periods representing principal energy levels.
Explanation: Horizontal rows are called periods. There are 7 periods representing principal energy levels.
4. Vertical columns are called:
Answer: B. Groups
Explanation: Elements in the same group have similar valence electrons and chemical properties.
Explanation: Elements in the same group have similar valence electrons and chemical properties.
5. Number of groups in modern periodic table:
Answer: C. 18
Explanation: The modern periodic table contains 18 vertical groups based on valence electron configuration.
Explanation: The modern periodic table contains 18 vertical groups based on valence electron configuration.
6. Alkali metals belong to group:
Answer: A. 1
Explanation: Group 1 elements have one valence electron and are highly reactive metals.
Explanation: Group 1 elements have one valence electron and are highly reactive metals.
7. Halogens are placed in group:
Answer: B. 17
Explanation: Halogens have 7 valence electrons and need one electron to complete octet.
Explanation: Halogens have 7 valence electrons and need one electron to complete octet.
8. Noble gases have valency:
Answer: D. 0
Explanation: Their outer shell is complete, so they neither gain nor lose electrons.
Explanation: Their outer shell is complete, so they neither gain nor lose electrons.
9. Atomic size decreases across a period because:
Answer: B. Increase in nuclear charge
Explanation: More protons pull electrons closer, reducing atomic radius.
Explanation: More protons pull electrons closer, reducing atomic radius.
10. Metallic character across a period:
Answer: B. Decreases
Explanation: Tendency to lose electrons decreases from left to right.
Explanation: Tendency to lose electrons decreases from left to right.
11. Metallic character down a group:
Answer: B. Increases
Explanation: Atomic size increases, electrons are lost more easily.
Explanation: Atomic size increases, electrons are lost more easily.
12. Most electronegative element:
Answer: B. Fluorine
Explanation: Fluorine has the highest tendency to attract electrons due to small size and high nuclear charge.
Explanation: Fluorine has the highest tendency to attract electrons due to small size and high nuclear charge.
13. Which property shows periodicity?
Answer: D. All of these
Explanation: These properties repeat at regular intervals when arranged by atomic number.
Explanation: These properties repeat at regular intervals when arranged by atomic number.
14. Isotopes are placed in same position because they have same:
Answer: B. Atomic number
Explanation: Chemical properties depend on atomic number, which is same for isotopes.
Explanation: Chemical properties depend on atomic number, which is same for isotopes.
15. Mendeleev arranged elements by:
Answer: B. Atomic mass
Explanation: Increasing atomic mass was the basis of Mendeleev’s periodic table.
Explanation: Increasing atomic mass was the basis of Mendeleev’s periodic table.
16. Lanthanides and Actinides are placed:
Answer: B. Separately at bottom
Explanation: To maintain table structure, f‑block elements are shown separately.
Explanation: To maintain table structure, f‑block elements are shown separately.
17. Valency across a period:
Answer: A. Increases then decreases
Explanation: It rises from 1 to 4 then falls to 0.
Explanation: It rises from 1 to 4 then falls to 0.
18. Reactivity of metals down the group:
Answer: B. Increases
Explanation: Loss of electrons becomes easier due to larger atomic size.
Explanation: Loss of electrons becomes easier due to larger atomic size.
19. Which is a metalloid?
Answer: B. Silicon
Explanation: Metalloids show properties of both metals and non‑metals.
Explanation: Metalloids show properties of both metals and non‑metals.
20. Periodic repetition of properties is due to repetition of:
Answer: C. Electronic configuration
Explanation: Similar valence shell configurations lead to repetition of chemical properties.
Explanation: Similar valence shell configurations lead to repetition of chemical properties.