Question:
Define Latent Heat of Fusion and Latent Heat of vaporisation.
Answer:
The latent heat of fusion of a substance is the quantity of heat required to convert one unit mass of the substance from solid state to the liquid state at its melting point without any change of temperature. The quantity of heat required to convert one unit mass of a liquid into vapour at its boiling point without any change of temperature is called its latent heat of vaporisation. [Another better definition provided by one of our read Mr. Saheel Deshpande is as follows:] Latent heat of vaporisation: It is the amount of heat consumed when 1 kg of liquid changes into vapor at constant temperature and pressure.
Matter in Our Surroundings
Q 1.
What is SI unit of temperature? Give mathematical relation also.
Q 3.
How matter is classified in terms of physical state?
Q 4.
What do you mean by change in state?
Q 5.
What is evaporation? Why does evaporation cause cooling?
Q 6.
Which state of matter is most easily compressible?
Q 7.
List any five physical properties of liquids.
Q 8.
Define the term Volatile Liquid.
Q 9.
What are the ways a gas can be liquefied?
Q 10.
What do you mean by the term Volume?
Q 11.
Why solids cannot be compressed like gases?
Q 12.
Define transpiration.
Q 13.
Arrange the following substances in increasing order of intermolecular force of attraction: water, sugar, oxygen
Q 15.
What are the differences between boiling and evaporation?
Q 16.
Define evaporation.
Q 17.
The mass per unit volume of a substance is called density (density=mass/volume). Arrange the following in order of increasing density:
Air, Exhaust from chimneys, Honey, Water, Chalk, Cotton and Iron.
Q 18.
What do you mean by the following terms:
a. Evaporation
b. Sublimation
c. Condensation
Q 19.
Define Latent Heat of Fusion and Latent Heat of vaporisation.
Q 20.
Our own bodies contain examples of all three states of matter. Can you identify these?
Q 21.
Why is light not considered matter?
Q 22.
How matter is classified in terms of composition?
Q 23.
How can matter change its state?
Q 24.
How vapour is different from gases? Give examples of each.
Q 25.
Why do diffusion become faster at higher temperatures?
Q 26.
Which of the following state does not exist at room temperature conditions: a) Solids b) Liquids c) Gas d) Plasma
Q 27.
In which case evaporation of water will be faster i.e. near the sea or far away from the sea.
Q 28.
Why do gases diffuse rapidly?
Q 29.
What is the physical state of water at the following temperatures? (a) 25 °C (b) 0 °C (c) 100 °C
Q 30.
Which of the following are matter?
Chair, Air, Love, Smell, Hate, Almonds, Thought, Cold, Cold drinks, Smell of perfume
Q 31.
Convert the following temperature to Celsius scale: (a) 300 K (b) 573 K
Q 32.
Convert the temperature of 373°C to the Kelvin scale.
Q 33.
What is meant by saying that the latent heat of vaporisation of water is 22.5 x
Q 34.
What is the (a) common unit of temperature, and (b) SI unit of temperature ?
Q 35.
Why does the temperature of a substance remain constant during melting and boiling even when heat is being supplied to it continuously?
Q 36.
Write the full forms of the following :(a) LPG (b) CNG
Q 37.
State whether the following statement is true or false : Solid carbon dioxide is stored under low pressure.
Q 38.
Convert the temperature of 573 K to the Celsius scale.
Q 39.
What are the conditions for 'something' to be called 'matter' ?
Q 40.
Name the process by which a drop of ink spreads in a beaker of water.
Q 41.
What is the general name of : (a) rigid form of matter ? (b) fluid forms of matter ?
Q 42.
(a) What is evaporation ? State the various factors which affect evaporation.
Why does evaporation cool a liquid ?
Q 43.
Define the following terms:
a. Melting point
b. Freezing point
c. Boiling point
Q 44.
Is smell of garlic or perfume a matter?
Q 45.
Honey is more viscous than water. Can you suggest why ?
Q 46.
What causes evaporation?
OR
Explain evaporation and its cooling effect in terms of kinetic energy of particles.
Q 47.
The Kelvin temperature is 270 K. What is the corresponding Celsius scale temperature ?
Q 48.
The Kelvin scale temperature is 0 K. What is the corresponding Celsius scale temperature ?
Q 49.
Give the usual name for the following :Heat required to change the state of a substance without changing the temperature.
Q 50.
What are the characteristics of matter?
