Q1. Convert the following temperatures to the Celsius scale
(a) 300K
(b)573K
Answer:
Subtract -273 from the temperature in Kelvin Scale to get the temperature in Celsius scale.
(a). 300K
( 300 - 273) = 27 o C
(b) 573 K
= (573 - 273) = 300 o C
Q2. Convert the following temperatures to kelvin scale
Answer:
Add 273 to the temperature in Celsius to get the temperature in Kelvin scale
(a) 25 o C
25 + 273 = 298 K
(b) 373 o C
373 + 273 = 646 K
Q3. Give reasons 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.
Answer:
(a) Due to the process of sublimation the naphthalene balls directly convert to vapours with the passage of time without leaving a trace.
(b) The particles of perfume mixes with air and spread out with air. Due to this reason the smell of perfumes travel several metres .
Q4. Arrange the following substances in increasing order of forces of attraction between the particles between the particles - water, sugar, oxygen
Answer. Oxygen(gas), water(liquid) , sugar (Solid)
The forces of attraction are greatest in solid, least in gases and intermediate for liquid.
Q5. What is the physical state of water at -
(a) 25 o C (b) 0 o C (c) 100 o C
Answer
(a) 25 o C - Liquid
(b) 0 o C-solid in ice form
(c) 100 o C - Gaseous in form of steam
Q6. Give reasons to justify -
(a)water at room temperature is a liquid
(b)an iron Amirah is a solid at room temperature.
Answer.
(a)
(i). Water at room temperature is liquid as it can take shape of the container in which it is poured.
(ii). force of attraction is weaker due to which it flows.
(b)
(i) The almirah has a rigid solid structure and has definite shape.
(ii) Due to strong forces of attraction the almirah retains its shape and size.
Q7. Why is ice at 273 K more effective in cooling than water at same temperature.
Answer: The ice particles at 273 K have less energy as compared to the water molecules at 273 K. Therefore, ice is more effective than water for cooling at 273K.
Q8. What produces more severe burns, boiling water or steam?
Answer: As compared to boiling water, the steam causes severe burns due to the fact that the steam possess more energy (latent heat of evaporation) .
Q9. Name A,B,C,D,E and F in the following diagrams showing change in its state.
Answer:
A- Fusion
B- Vaporization
C- Condensation
D- Solidification
E- Sublimation
F- Sublimation
next : Chapter 2
(a) 300K
(b)573K
Answer:
Subtract -273 from the temperature in Kelvin Scale to get the temperature in Celsius scale.
(a). 300K
( 300 - 273) = 27 o C
(b) 573 K
= (573 - 273) = 300 o C
Q2. Convert the following temperatures to kelvin scale
Answer:
Add 273 to the temperature in Celsius to get the temperature in Kelvin scale
(a) 25 o C
25 + 273 = 298 K
(b) 373 o C
373 + 273 = 646 K
Q3. Give reasons 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.
Answer:
(a) Due to the process of sublimation the naphthalene balls directly convert to vapours with the passage of time without leaving a trace.
(b) The particles of perfume mixes with air and spread out with air. Due to this reason the smell of perfumes travel several metres .
Q4. Arrange the following substances in increasing order of forces of attraction between the particles between the particles - water, sugar, oxygen
Answer. Oxygen(gas), water(liquid) , sugar (Solid)
The forces of attraction are greatest in solid, least in gases and intermediate for liquid.
Q5. What is the physical state of water at -
(a) 25 o C (b) 0 o C (c) 100 o C
Answer
(a) 25 o C - Liquid
(b) 0 o C-solid in ice form
(c) 100 o C - Gaseous in form of steam
Q6. Give reasons to justify -
(a)water at room temperature is a liquid
(b)an iron Amirah is a solid at room temperature.
Answer.
(a)
(i). Water at room temperature is liquid as it can take shape of the container in which it is poured.
(ii). force of attraction is weaker due to which it flows.
(b)
(i) The almirah has a rigid solid structure and has definite shape.
(ii) Due to strong forces of attraction the almirah retains its shape and size.
Q7. Why is ice at 273 K more effective in cooling than water at same temperature.
Answer: The ice particles at 273 K have less energy as compared to the water molecules at 273 K. Therefore, ice is more effective than water for cooling at 273K.
Q8. What produces more severe burns, boiling water or steam?
Answer: As compared to boiling water, the steam causes severe burns due to the fact that the steam possess more energy (latent heat of evaporation) .
Q9. Name A,B,C,D,E and F in the following diagrams showing change in its state.
Answer:
A- Fusion
B- Vaporization
C- Condensation
D- Solidification
E- Sublimation
F- Sublimation
next : Chapter 2
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