Chapter 1
Mater In Our Surroundings
Page-3
Questions-
1. Which of the following are matter?
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2. Give reasons for the following observation:
The smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go close.
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3. A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
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4. What are the characteristics of the particles of matter?
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Page-6
Questions-
1. The mass per unit volume of a substance is called density.
(denisty = mass / volume). Arrange the following in order of increasing density - air, exhaust from chimneys, honey water, chalk cotton and iron.
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2. (a) Tabulate the differences in the characteristics of states of matter.
(b) Comment upon the following: rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and denisty.
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3. Give reasons
(a) A gas fills completely the vessel in which it is kept.
(b) A gas exerts pressure on the walls of the container.
(c) A wooden table should be called a solid.
(d) We can easily move our hand in air but to do the same through a solid black of wood we need a karate expert.
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4. Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why.
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Page-9
Questions-
1. convert the following temperature to celsius scale.
a. 300k b. 573k.
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2. What is the physical state of water at:
a. 250ºC b. 100ºC
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3. For any substance. why does the temperature remain constant during the change of state?
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4. Suggest a method to liquefy atmospheric gasses.
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Page-10
Questions-
1. Why does a desert cooler cool better on a hot dry day?
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2. How does the water kept in an earthen pot (matka) become cool during summer?
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3. Why does our palm feel cold when we put some acetone or petrol or perfume on it?
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4. Why are we able to sip hot tea or milk faster from a saucer rather than a cup?
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5. What type of clothes should we wear in summer?
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Page-12
Exercises-
1. Convert the following temperatures to the celsius scale.
(a) 293 K (b) 470 K
2. Convert the following temperatures to the kelvin scale.
(a) 25° C (b) 373° C
3. Give reason for the following observations.
(a) Naphthalene balls disappear with time without leaving any solid.
(b) We can get the smell of perfume sitting several metres away.
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4. Arrange the following substances in increasing order of forces of attraction between the particles- Water, Sugar, Oxygen.
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5. What is the physical state of water at-
(a) 25ºC (b) 0ºC (c) 100ºC
(ক) 25ºC (খ) 0ºC (গ) 100ºC
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6. Give two reasons to justify-
(a) Water at room temperature is liquid.
(b) an iron almirah is a solid at room temperature.
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7. Why is ice at 273 k more effective in cooling than water or steam?
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8. What produces more severe burns, boiling water or steam?
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9. Name A, B, C, D, E And F in the following diagram showing change in its state
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