Question:
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.
Answer:
Particles present in the matter possess kinetic energy and therefore move constantly. At lower temperature, particles have low kinetic energy and thus move slowly. But as soon as the temperature rises, these particles move faster than when they were in cold. As the particles of hot vapours coming out of hot sizzling food move faster, they can reach several meters away. The particles in the cold food move slowly and thus do not reach us when we are away even a few meters. Therefore we have to go closer to smell cold food.
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.
Which of the following are matter?
Chair, Air, Love, Smell, Hate, Almonds, Thought, Cold, Cold drinks, Smell of perfume
Q 6.
What are the differences between boiling and evaporation?
Q 7.
Define transpiration.
Q 8.
What is evaporation? Why does evaporation cause cooling?
Q 9.
How matter is classified in terms of physical state?
Q 10.
Define the term Volatile Liquid.
Q 11.
What do you mean by the following terms:
a. Evaporation
b. Sublimation
c. Condensation
Q 12.
Which state of matter is most easily compressible?
Q 13.
Define Latent Heat of Fusion and Latent Heat of vaporisation.
Q 15.
What do you mean by the term Volume?
Q 16.
What are the ways a gas can be liquefied?
Q 17.
Our own bodies contain examples of all three states of matter. Can you identify these?
Q 18.
How can matter change its state?
Q 19.
List any five physical properties of liquids.
Q 20.
Explain compressibility in gases with an example?
Q 21.
Why solids cannot be compressed like gases?
Q 22.
How matter is classified in terms of composition?
Q 23.
Arrange the following substances in increasing order of intermolecular force of attraction: water, sugar, oxygen
Q 24.
Why do diffusion become faster at higher temperatures?
Q 25.
Define evaporation.
Q 26.
What is the physical state of water at the following temperatures? (a) 25 °C (b) 0 °C (c) 100 °C
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.
Give the usual name for the following :Heat required to change the state of a substance without changing the temperature.
Q 42.
The Kelvin scale temperature is 0 K. What is the corresponding Celsius scale temperature ?
Q 43.
(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 44.
What is meant by saying that the latent heat of vaporisation of water is 22.5 x
Q 45.
What is the general name of : (a) rigid form of matter ? (b) fluid forms of matter ?
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.
Name the process by which a drop of ink spreads in a beaker of water.
Q 50.
Write the relation between Kelvin scale and Celsius scale of temperature.
