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3. Atoms and Molecules Science class 9 in English Medium ncert book solutions Additional -Questions 3
3. Atoms and Molecules Additional -Questions 3 – Complete NCERT Book Solutions for Class 9 Science (English Medium). Get all chapter explanations, extra questions, solved examples and additional practice questions for 3. Atoms and Molecules Additional -Questions 3 to help you master concepts and score higher.
3. Atoms and Molecules Science class 9 in English Medium ncert book solutions Additional -Questions 3
NCERT Solutions for Class 9 Science play an important role in helping students understand the concepts of the chapter 3. Atoms and Molecules clearly. This chapter includes the topic Additional -Questions 3, which is essential from both academic and examination point of view. The solutions provided here are prepared strictly according to the latest NCERT syllabus and follow the guidelines of CBSE to ensure accuracy and relevance. Each question is explained in a simple and student-friendly manner so that learners can grasp the concepts without confusion. These NCERT Solutions are useful for regular study, homework help, and exam preparation. All textbook questions are solved step by step to improve problem-solving skills and conceptual clarity. Students of Class 9 studying Science can use these solutions to revise important topics, understand difficult questions, and practise effectively before examinations. The chapter 3. Atoms and Molecules is explained in a structured way, making it easier for students to connect the theory with the topic Additional -Questions 3. By studying these updated NCERT Solutions for Class 9 Science, students can build a strong foundation, boost their confidence, and score better marks in school and board exams.
3. Atoms and Molecules
Additional -Questions 3
Additional -Questions:
Q1. What is atomicity?
Ans: The number of atoms contained in a molecule of a substance is called its atomicity.
Q2. How molecules are categrised on the base of atomicity?
Ans:
1. Monoatomic Molecules (Molecule having 1 atom)
2. Diatomic Molecules (molecule having 2 atoms)
3. Triatomic Molecules (molecules having 3 atoms)
4. Tetraatomic Molecules (molecules having 4 atoms)
5. Ployatomic Molecules (molecules having more than 4 molecules)
1. Atom
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The smallest particle of an element that cannot be divided further by chemical means.
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It retains all the properties of that element.
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Example: H (Hydrogen atom), O (Oxygen atom).
2. Molecule
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A group of two or more atoms (same or different) chemically bonded together.
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Example: H₂ (hydrogen molecule), H₂O (water molecule).
3. Ion
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A charged particle formed when an atom or molecule loses or gains electrons.
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Positive ions → Cations (formed by loss of electrons).
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Negative ions → Anions (formed by gain of electrons).
4. Atomicity
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The number of atoms present in one molecule of an element.
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Example:
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O₂ → Atomicity = 2
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P₄ → Atomicity = 4
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5. Anion
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A negatively charged ion.
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Formed by gain of electrons.
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Example: Cl⁻, O²⁻.
6. Cation
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A positively charged ion.
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Formed by loss of electrons.
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Example: Na⁺, Ca²⁺.
7. One mole atom
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The amount of a substance containing 6.022 × 10²³ atoms of that element.
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Example: 1 mole of carbon = 6.022 × 10²³ atoms of carbon.
8. One mole molecule
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The amount of a substance containing 6.022 × 10²³ molecules.
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Example: 1 mole of water (H₂O) = 6.022 × 10²³ molecules of H₂O.
9. Monoatomic
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A molecule that contains only one atom.
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Example: Noble gases (He, Ne, Ar).
10. Diatomic
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A molecule that contains two atoms.
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Example: H₂, O₂, Cl₂.
11. Triatomic
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A molecule that contains three atoms.
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Example: O₃ (ozone), H₂O (water).
12. Polyatomic
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A molecule that contains more than three atoms.
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Example: P₄ (phosphorus), CH₄ (methane), C₆H₁₂O₆ (glucose).
See other sub-topics of this chapter:
1. Chapter Review 2. Text-book Questions 3. Additional -Questions 4. Additional -Questions 2 5. Additional -Questions 3