# NCERT Class 9 Science Chapter 9 Atomic Foundations of Matter Solutions: In-Text and Exercise Questions Explained | SwaVid This document provides the in-text and end-of-chapter exercise questions from the new NCERT Class 9 Science textbook, "Exploration", Chapter 9 "Atomic F... Canonical: https://swavid.com/science/class/9/chapter/atomic-foundations-of-matter/ncert-solutions Source: https://swavid.com/science/class/9/chapter/atomic-foundations-of-matter/ncert-solutions # Atomic Foundations of Matter ## Find the gaps before this chapter finds them for you. ## Related chapters Chapter 9 · Class 9 Science This document provides the in-text and end-of-chapter exercise questions from the new NCERT Class 9 Science textbook, "Exploration", Chapter 9 "Atomic Foundations of Matter", along with detailed step-by-step solutions. Your study route In-text Questions (Think It Over / Pause and Ponder) Answer: Yes, pure samples of water from any source are chemically identical because water is a compound with a fixed composition (H₂O), adhering to the Law of Constant Proportions. However, natural water samples often contain varying impurities, which means the overall samples might not be identical in their complete composition. [17, 21] End-of-Chapter Exercise Questions (Revise, Reflect, Refine - Page 182) Before you push ahead Most stuck chapters trace back to one earlier idea. Check the prerequisites first, or let SwaVid adapt this chapter to the way your child learns. Keep exploring Class 9 Source - Pure water is a chemical compound with a fixed chemical formula, H₂O. This means it always consists of hydrogen and oxygen atoms combined in a fixed ratio of 1:8 by mass, and 2:1 by number of atoms. [17, 21] - According to the Law of Constant Proportions, a pure chemical compound always contains the same elements in the same fixed proportions by mass, regardless of its source or method of preparation. [15, 16] - Therefore, pure samples of water from any source (e.g., river, well, ocean, rain) are chemically identical in their composition (H₂O). [17, 21] - However, natural water samples often contain dissolved salts, gases, dust, and other impurities. These impurities can vary depending on the source. [17] - So, while the pure water component (H₂O) is identical, the overall 'samples' of water from different sources might not be chemically identical due to varying impurities. [17] - NCERT Class 9 Science textbook: Exploration : Chapter 9: Atomic Foundations of Matter ## Key Links - [NCERT Science](https://swavid.com/science) - [Class 9](https://swavid.com/science/class/9) - [Start with concepts](https://swavid.com/science/class/9/chapter/atomic-foundations-of-matter) - [Check a prerequisite](https://swavid.com/learning-debt-identifier) - [Concepts](https://swavid.com/science/class/9/chapter/atomic-foundations-of-matter) - [Practice](https://swavid.com/science/class/9/chapter/atomic-foundations-of-matter/practice-questions) - [NCERT Solutions](https://swavid.com/science/class/9/chapter/atomic-foundations-of-matter/ncert-solutions) - [Find the gaps before this chapter](https://swavid.com/learning-debt-identifier) - [Learn this chapter adapted to you](https://swavid.com/learning-style-test) - [Previous chapter 8 . Journey Inside the Atom](https://swavid.com/science/class/9/chapter/journey-inside-the-atom) - [Next chapter 10 . Sound Waves: Characteristics and Applications](https://swavid.com/science/class/9/chapter/sound-waves-characteristics-and-applications) - [All Class 9 chapters](https://swavid.com/science/class/9) - [8 Journey Inside the Atom Discovery of Subatomic Particles · Atomic Models: Thomson, Rutherford, and Bohr Open chapter](https://swavid.com/science/class/9/chapter/journey-inside-the-atom) - [10 Sound Waves: Characteristics and Applications Characteristics of Sound Waves · Speed of Sound Open chapter](https://swavid.com/science/class/9/chapter/sound-waves-characteristics-and-applications) - [7 Work, Energy, and Simple Machines Work Done by a Force · Energy: Forms and Transformations Open chapter](https://swavid.com/science/class/9/chapter/work-energy-and-simple-machines) - [NCERT Class 9 Science textbook: Exploration](https://ncert.nic.in/textbook.php)