Скачать или смотреть 5. Changes Around Us: Physical and Chemical (Question Answer) | Grade 7 Science - Curiosity

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In this video, we will study Question answers of Chapter 5 - "Changes Around Us: Physical and Chemical". This chapter is taken from Grade 7 NCERT Science Textbook - "Curiosity".

Short Notes of this chapter:    • 5. Changes Around Us: Physical and Chemica...  

List of questions answered in the video:
0:12 - 1. Which of the following statements are the characteristics of a physical change?
0:31 - 2. Predict which of the following changes can be reversed and which cannot be reversed. If you are not sure, you may write that down. Why are you not sure about these?
1:57 - 3. State whether the following statements are True or False. In case a statement is False, write the correct statement.
2:31 - 4. Fill in the blanks in the following statements:
3:13 - 5. Are the changes of water to ice and water to steam, physical or chemical? Explain.
3:32 - 6. Is curdling of milk a physical or chemical change? Justify your statement.
3:46 - 7. Natural factors, such as wind, rain, etc., help in the formation of soil from rocks. Is this change physical or chemical and why?
4:10 - 8. Read the following story titled ‘Eco-friendly Prithvi’, and tick the most appropriate option(s) given in the brackets. Provide a suitable title of your choice for the story.
5:33 - 9. Some changes are given here. Write physical changes in the area marked ‘A’ and chemical changes in the area marked ‘B’. Enter the changes which are both physical and chemical in the area marked ‘C’.
6:26 - 10. The experiments shown in Fig. 5.11a, b, c, and d were performed. Find out in which case(s) did lime water turn milky and why?
6:59 - Write a message on a piece of paper using lemon juice as ink and let it dry. The message will become invisible. Now use a warm iron over the paper (or hold the paper over the flame of a candle, taking care that it does not catch fi re). The invisible letters turn dark brown as the paper gets warm. Can any of these changes be reversed?
7:40 - We hear a lot of news about landslides and breaking of rocks in hilly regions these days, causing a lot of damage to life and property. Discuss what steps we can take to reduce landslides and rock erosion.
8:15 - Observe the activities going on in the kitchen and note any changes that can be reversed. Are these physical or chemical changes?
8:58 - Yeast is added while baking bread to make it fluffy and soft. How does yeast work? Try and find out!
10:45 - Chameleons (Girgits) change colour to blend in with their surroundings and also when they are angry or sense danger (Fig. 5.12). Is this a change that can be reversed? Explore from the internet or from your school library.

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