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 2.
What do you mean by change in state?
Q 3.
What is SI unit of temperature? Give mathematical relation also.
Q 4.
Why is light not considered matter?
Q 5.
Define transpiration.
Q 6.
What are the differences between boiling and evaporation?
Q 7.
Which of the following are matter?
Chair, Air, Love, Smell, Hate, Almonds, Thought, Cold, Cold drinks, Smell of perfume
Q 8.
Define the term Volatile Liquid.
Q 9.
How matter is classified in terms of physical state?
Q 10.
What is evaporation? Why does evaporation cause cooling?
Q 11.
Which state of matter is most easily compressible?
Q 12.
What do you mean by the following terms:
a. Evaporation
b. Sublimation
c. Condensation
Q 14.
Define Latent Heat of Fusion and Latent Heat of vaporisation.
Q 15.
What do you mean by the term Volume?
Q 16.
Our own bodies contain examples of all three states of matter. Can you identify these?
Q 17.
What are the ways a gas can be liquefied?
Q 18.
How can matter change its state?
Q 19.
How matter is classified in terms of composition?
Q 20.
Why solids cannot be compressed like gases?
Q 21.
List any five physical properties of liquids.
Q 22.
Explain compressibility in gases with an example?
Q 23.
Arrange the following substances in increasing order of intermolecular force of attraction: water, sugar, oxygen
Q 24.
Define evaporation.
Q 25.
What is the physical state of water at the following temperatures? (a) 25 °C (b) 0 °C (c) 100 °C
Q 26.
Why do diffusion become faster at higher temperatures?
Q 27.
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 28.
Convert the following temperature to Celsius scale: (a) 300 K (b) 573 K
Q 29.
What are the characteristics of matter?
Q 30.
Why does the temperature of a substance remain constant during melting and boiling even when heat is being supplied to it continuously?
Q 31.
In which case evaporation of water will be faster i.e. near the sea or far away from the sea.
Q 32.
Define the following terms:
a. Melting point
b. Freezing point
c. Boiling point
Q 33.
Why does steam cause more severe burns than boiling water, though both are at the same temperature?
Q 34.
How vapour is different from gases? Give examples of each.
Q 35.
Which of the following state does not exist at room temperature conditions: a) Solids b) Liquids c) Gas d) Plasma
Q 36.
Why do gases diffuse rapidly?
Q 37.
Why is ice at 273 K more effective in cooling than water at the same temperature?
Q 38.
What factors affect the rate of evaporation?
Q 39.
Convert the temperature of 573 K to the Celsius scale.
Q 40.
A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
Q 41.
The Kelvin scale temperature is 0 K. What is the corresponding Celsius scale temperature ?
Q 42.
(a) Define the term 'latent heat of vaporisation' of a liquid. What is the value of the latent heat of vaporisation of water ?
(b) Draw a labelled diagram of the experimental set-up to study the latent heat of vaporisation of water.
Q 43.
Give the usual name for the following :Heat required to change the state of a substance without changing the temperature.
Q 44.
What is the general name of : (a) rigid form of matter ? (b) fluid forms of matter ?
Q 45.
What is meant by saying that the latent heat of vaporisation of water is 22.5 x
Q 46.
Give reasons to justify: (a) Water at room temperature is a liquid. (b) An iron almirah is solid.
Q 47.
What is the scientific name of particles which make up matter ?
Q 48.
Convert the temperature of 373°C to the Kelvin scale.
Q 49.
Write the relation between Kelvin scale and Celsius scale of temperature.
Q 50.
Name the process by which a drop of ink spreads in a beaker of water.
