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.
What do you mean by the term Volume?
Q 4.
What do you mean by change in state?
Q 5.
Which state of matter is most easily compressible?
Q 6.
List any five physical properties of liquids.
Q 7.
What are the ways a gas can be liquefied?
Q 8.
How matter is classified in terms of physical state?
Q 9.
Define the term Volatile Liquid.
Q 10.
What is evaporation? Why does evaporation cause cooling?
Q 11.
Arrange the following substances in increasing order of intermolecular force of attraction: water, sugar, oxygen
Q 12.
Define transpiration.
Q 13.
Why solids cannot be compressed like gases?
Q 15.
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 16.
What are the differences between boiling and evaporation?
Q 17.
How matter is classified in terms of composition?
Q 18.
Define evaporation.
Q 19.
What do you mean by the following terms:
a. Evaporation
b. Sublimation
c. Condensation
Q 20.
Why is light not considered matter?
Q 21.
Define Latent Heat of Fusion and Latent Heat of vaporisation.
Q 22.
Our own bodies contain examples of all three states of matter. Can you identify these?
Q 23.
How can matter change its state?
Q 24.
Why do diffusion become faster at higher temperatures?
Q 25.
What is the physical state of water at the following temperatures? (a) 25 °C (b) 0 °C (c) 100 °C
Q 26.
How vapour is different from gases? Give examples of each.
Q 27.
Which of the following are matter?
Chair, Air, Love, Smell, Hate, Almonds, Thought, Cold, Cold drinks, Smell of perfume
Q 28.
In which case evaporation of water will be faster i.e. near the sea or far away from the sea.
Q 29.
Convert the following temperature to Celsius scale: (a) 300 K (b) 573 K
Q 30.
Explain compressibility in gases with an example?
Q 31.
Why does the temperature of a substance remain constant during melting and boiling even when heat is being supplied to it continuously?
Q 32.
Which of the following state does not exist at room temperature conditions: a) Solids b) Liquids c) Gas d) Plasma
Q 33.
Why do gases diffuse rapidly?
Q 34.
What are the characteristics of matter?
Q 35.
Define the following terms:
a. Melting point
b. Freezing point
c. Boiling point
Q 36.
Explain with an experiment to show gases do not have fixed shape or volume.
Q 37.
What factors affect the rate of evaporation?
Q 38.
The Kelvin scale temperature is 0 K. What is the corresponding Celsius scale temperature ?
Q 39.
Give reasons to justify: (a) Water at room temperature is a liquid. (b) An iron almirah is solid.
Q 40.
Convert the temperature of 573 K to the Celsius scale.
Q 41.
Give the usual name for the following :Heat required to change the state of a substance without changing the temperature.
Q 42.
Name the process by which a drop of ink spreads in a beaker of water.
Q 43.
What is the scientific name of particles which make up matter ?
Q 44.
The Kelvin temperature is 270 K. What is the corresponding Celsius scale temperature ?
Q 45.
Is smell of garlic or perfume a matter?
Q 46.
Write the relation between Kelvin scale and Celsius scale of temperature.
Q 47.
Give reasons for the following observations. The smell of hot sizzling food reaches you several meters away, but to get smell from cold food you have to go close.
Q 48.
A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
Q 49.
What are the conditions for 'something' to be called 'matter' ?
Q 50.
Honey is more viscous than water. Can you suggest why ?
