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Changes Around Us: Physical and Chemical

CBSE · Class 7 · Science

Flashcards for Changes Around Us: Physical and Chemical — CBSE Class 7 Science. Quick Q&A cards covering key concepts, definitions, and formulas.

42 questions60 flashcards5 concepts

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60 Flashcards
Card 1Physical changes

What is a physical change?

Answer

A physical change is a change in shape, size, or state of a substance, and no new substance is formed. Melting ice, folding paper, and crushing chalk are physical changes.

Card 2शारीरिक परिवर्तन

भौतिक परिवर्तन क्या है?

Answer

भौतिक परिवर्तन किसी पदार्थ के आकार, माप या अवस्था में परिवर्तन है और कोई नया पदार्थ नहीं बनता है। बर्फ का पिघलना, कागज को मोड़ना, चाक को कुचलना भौतिक परिवर्तन हैं।

Card 3Chemical changes

What is a chemical change?

Answer

A chemical change is a change in which one or more new substances are formed through a chemical reaction. Lime water turning milky, rusting, and burning magnesium are chemical changes.

Card 4रासायनिक परिवर्तन

रासायनिक परिवर्तन क्या है?

Answer

रासायनिक परिवर्तन एक ऐसा परिवर्तन है जिसमें रासायनिक अभिक्रिया के द्वारा एक या एक से अधिक नए पदार्थ बनते हैं। चूने का पानी दूधिया होना, जंग लगना, मैग्नीशियम का जलना रासायनिक परिवर्तन हैं।

Card 5Lime water test

Why does lime water turn milky when exhaled air is passed through it?

Answer

Exhaled air contains carbon dioxide. It reacts with lime water and forms calcium carbonate, which is a new white insoluble substance. That is why the liquid turns milky.

Card 6चुनका पानी परीक्षण

जब चूने के पानी से साँस की हवा निकाली जाती है तो वह दूधिया क्यों हो जाता है?

Answer

निःश्वासित वायु में कार्बन डाइआक्साइड होता है। यह चूने के पानी के साथ प्रतिक्रिया करके कैल्शियम कार्बोनेट बनाता है, जो एक नया सफेद अघुलनशील पदार्थ है। इसी कारण तरल दूधिया हो जाता है।

Card 7Chemical equations

What is the chemical equation for the lime water test?

Answer

Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water. Lime water is calcium hydroxide, and the new insoluble substance formed is calcium carbonate.

Card 8रासायनिक समीकरण

चूने के पानी के परीक्षण के लिए रासायनिक समीकरण क्या है?

Answer

कैल्शियम हाइड्रॉक्साइड + कार्बन डाइआक्साइड → कैल्शियम कार्बोनेट + जल चूने का जल कैल्शियम हाइड्रॉक्साइड है, नया अघुलनशील पदार्थ कैल्शियम कार्बोनेट है।

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Frequently Asked Questions

What are the important topics in Changes Around Us: Physical and Chemical for CBSE Class 7 Science?
Changes Around Us: Physical and Chemical covers several key topics that are frequently asked in CBSE Class 7 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
How to score full marks in Changes Around Us: Physical and Chemical — CBSE Class 7 Science?
Understand the core concepts first, then work through the 42 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.
How many flashcards are available for Changes Around Us: Physical and Chemical?
There are 60 flashcards for Changes Around Us: Physical and Chemical covering key definitions, formulas, and concepts. Use them daily for 10–15 minutes for best results.

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