Hello, Students for your better preparation for CBSE CLASS 6 here we are sharing the complete solution of NCERT CLASS 6 Science Chapter 6 Changes Around Us – with Complete explanation, Summary, NCERT CLASS 6 Science Short Answer Questions, NCERT CLASS 6 Science Long Answers, NCERT CLASS 6 Science MCQS, NCERT CLASS 6 Science mind maps.
Changes Around Us
Expansion and Contraction As temperatures shift, particles in substances can either expand or contract. When expansion occurs, the material undergoes a change, becoming more open or loose. Conversely, contraction involves particles becoming tighter or denser, signifying another kind of alteration. The extent of these changes varies depending on whether the substance is a solid, liquid, or gas.
States of Matter Shift Physical changes occur when substances transition from one state of matter to another. An illustrative case is water, capable of existing in solid, liquid, and gas forms. In frigid temperatures, water takes on a solid state as ice. When heat is applied, the ice melts and becomes liquid water, a phenomenon known as melting. Further temperature elevation turns water into vapor through evaporation. Reverting vapor to its liquid state is achieved through condensation, a process initiated by temperature reduction.
Unusual Water Expansion A distinctive attribute of water is its anomalous expansion during cooling. While it contracts until reaching 4°C, it defies the norm by expanding as the temperature drops further from 4°C to 0°C, a phenomenon aptly labeled the anomalous expansion of water.
Combustion Irreversible change occurs during combustion, leading to the creation of novel materials. Substances burn, yielding ash and gases as products. Consider the example of paper burning, resulting in ash with distinct properties and appearance compared to paper.
Segregation Separating components in a mixture or impure substance serves various essential purposes:
- Elimination of undesirable or harmful elements.
- Extraction of valuable components.
- Purification by removing impurities to attain a pristine sample.