Class 7 Science - MAHARASHTRA
Changes Around Us: Physical and Chemical
The Chapter 'Changes Around Us: Physical and Chemical' in Class 7 Science explores the various changes taking place in our daily lives, categorizing them into physical and chemical changes. Students will learn how physical changes are temporary and do not form new substances, while chemical changes result in the formation of entirely new substances with different properties. Understanding these concepts helps students differentiate between reversible processes like melting ice and irreversible ones like rusting iron or burning paper. This chapter is highly important for the Maharashtra (MSBSHSE) board exams as it builds the foundational chemical and physical principles required for higher-grade science.
Start Learning FreeKey Concepts
Physical Change
A change in which only the shape, size, state, or color of a substance changes, but no new substance is formed. These changes are usually temporary and reversible.
Chemical Change
A change in which one or more new substances are formed with entirely different properties from the original substances. These changes are usually permanent and irreversible.
Reversible Change
A change that can be undone to get back the original substance, such as freezing water into ice or dissolving salt in water.
Irreversible Change
A change that cannot be reversed to get back the original substance, such as baking a cake, burning a matchstick, or ripening of a fruit.
Rusting of Iron
A chemical process where iron reacts with oxygen and moisture in the air to form a brown flaky layer called rust, creating a new substance (iron oxide).
Important Formulas
Board Exam Info
This chapter typically carries around 4 to 6 marks in the Maharashtra (MSBSHSE) science examinations. Common question types include distinguishing between physical and chemical changes, giving reasons for everyday phenomena (like why rusting is a chemical change), and identifying whether a given process is reversible or irreversible.
Frequently Asked Questions
Is melting of wax a physical or chemical change?
Melting of wax is a physical change because only the solid wax turns into liquid wax without forming any new substance, and it can solidify back when cooled.
Why is burning of paper a chemical change?
Burning of paper is a chemical change because it produces completely new substances like ash, carbon dioxide, and water vapor, and it cannot be reversed.
Can a physical change be accompanied by a chemical change?
Yes, sometimes both occur together. For example, when a candle burns, the solid wax first melts (physical change), and then the vaporized wax burns to produce light, heat, and new gases (chemical change).
Learn Changes Around Us: Physical and Chemical with Your AI Tutor
10 different ways to study this chapter. Free for 3 chapters per day.
Lecture
Key Points
Interactive
Quiz
Flashcards