EXERCISE(matter in our surrounding)
1. Convert the following temperature to Celsius scale:
(a) 300 K
= 300°C
1. Convert the following temperature to Celsius scale:
(a) 300 K
► 300 K = (300 - 273)°C
= 27°C
= 27°C
(b) 573 K
► 573 K = (573 - 273)°C= 300°C
2. Convert the following temperatures to Kelvin scale.
(a) 25°C
►25 °C = (25 + 273) K
= 298 K
(b) 373°C
► 373 °C = (373 + 273) K
= 646 K
(a) 25°C
►25 °C = (25 + 273) K
= 298 K
(b) 373°C
► 373 °C = (373 + 273) K
= 646 K
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.
(a) Naphthalene balls disappear with time without leaving any solid because they undegoes sublimation easily i.e., the change of state of naphthalene from solid to gas takes place easily.
(b) Perfumes has high degree of vaporization and its vapour diffuse into air easily. Therefore, we can get the smell of perfume sitting several metres away.
(a) Naphthalene balls disappear with time without leaving any solid.
(b) We can get the smell of perfume sitting several metres away.
(a) Naphthalene balls disappear with time without leaving any solid because they undegoes sublimation easily i.e., the change of state of naphthalene from solid to gas takes place easily.
(b) Perfumes has high degree of vaporization and its vapour diffuse into air easily. Therefore, we can get the smell of perfume sitting several metres away.
4. Arrange the following substances in increasing order of forces of attraction between particles-- water, sugar, oxygen.
Oxygen, Water, Sugar.
5. What is the physical state of water at-
(a) 25°C
► Liquid State
(b) 0°C
► Solid State, can also be in liquid state(conditions required).
(c) 100°C
► Gaseous State, can also be in liquid state(conditions required).
6. Give two reasons to justify-
(a) water at room temperature is a liquid.
(b) an iron almirah is a solid at room temperature.
(a) Water at room temperature is a liquid because it has fluidity also it has no shape but has a fixed volume that is, it occupies the shape of the container in which it is kept.
(b) An iron almirah is a solid at room temperature it has rigid and fixed shape.
7. Why is ice at 273 K more effective in cooling than water at the same temperature?
Ice at 273 K has less energy than water (although both are at the same temperature). Water possesses the additional latent heat of fusion. Hence, at 273 K, ice is more effective in cooling than water.
8. What produces more severe burns, boiling water or steam?
Steam has more energy than boiling water. It possesses the additional latent heat of vaporization. Therefore, burns produced by steam are more severe than those produced by boiling water.
9. Name A, B, C, D, E and F in the following diagram showing change in its state.
CHAPTER-2
THE FUNDAMENTAL UNIT LIFE
1). why water come out from cucumber when we pour salt ? The salt cause water to be drawn out of the cucumber. Water is drawn to it because it goes from a higher concentration of water to lower concentration. When there is random motion that will always happen and is called diffusion. Osmosis is a type of diffusion that involves a semipermeable membrane or a membrane like exists in the cells of cucumbers that allows water through but not the salt. That is why it is called semipermeable. Only some things gets through the membrane. When there is more salt dissolved in the water on one side of the membrane compared to the other there is less water on that side. They call that hypertonic. Water will move from the higher concentration hypotonic side to the lower concentration of water on the hypertonic side. That is how you should think of it. It will often be exosmosispress as more salt but you should think of it as more salt dissolved actually means less water. Water will diffuse from higher concentration of water (lower salt) to lower concentration (higher salt). Think of it like this. If you had 50 people in a single room and 20 in the other during a party and they were all moving around randomly. After an hour there will be fewer people in the crowded room if they move around randomly. That is why diffusion goes from higher concentration to lower. Just don't be confused when they say higher concentration of salt. High salt means less water. The water molecules are what moves around and when it involves a semipermeable membrane like in most living cells it is called
(a) 25°C
► Liquid State
(b) 0°C
► Solid State, can also be in liquid state(conditions required).
(c) 100°C
► Gaseous State, can also be in liquid state(conditions required).
6. Give two reasons to justify-
(a) water at room temperature is a liquid.
(b) an iron almirah is a solid at room temperature.
(a) Water at room temperature is a liquid because it has fluidity also it has no shape but has a fixed volume that is, it occupies the shape of the container in which it is kept.
(b) An iron almirah is a solid at room temperature it has rigid and fixed shape.
7. Why is ice at 273 K more effective in cooling than water at the same temperature?
Ice at 273 K has less energy than water (although both are at the same temperature). Water possesses the additional latent heat of fusion. Hence, at 273 K, ice is more effective in cooling than water.
8. What produces more severe burns, boiling water or steam?
Steam has more energy than boiling water. It possesses the additional latent heat of vaporization. Therefore, burns produced by steam are more severe than those produced by boiling water.
9. Name A, B, C, D, E and F in the following diagram showing change in its state.
CHAPTER-2
THE FUNDAMENTAL UNIT LIFE
1). why water come out from cucumber when we pour salt ? The salt cause water to be drawn out of the cucumber. Water is drawn to it because it goes from a higher concentration of water to lower concentration. When there is random motion that will always happen and is called diffusion. Osmosis is a type of diffusion that involves a semipermeable membrane or a membrane like exists in the cells of cucumbers that allows water through but not the salt. That is why it is called semipermeable. Only some things gets through the membrane. When there is more salt dissolved in the water on one side of the membrane compared to the other there is less water on that side. They call that hypertonic. Water will move from the higher concentration hypotonic side to the lower concentration of water on the hypertonic side. That is how you should think of it. It will often be exosmosispress as more salt but you should think of it as more salt dissolved actually means less water. Water will diffuse from higher concentration of water (lower salt) to lower concentration (higher salt). Think of it like this. If you had 50 people in a single room and 20 in the other during a party and they were all moving around randomly. After an hour there will be fewer people in the crowded room if they move around randomly. That is why diffusion goes from higher concentration to lower. Just don't be confused when they say higher concentration of salt. High salt means less water. The water molecules are what moves around and when it involves a semipermeable membrane like in most living cells it is called
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