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 1.
What is SI unit of temperature? Give mathematical relation also.
Q 3.
What do you mean by change in state?
Q 4.
Why is light not considered matter?
Q 5.
Define the term Volatile Liquid.
Q 6.
Which state of matter is most easily compressible?
Q 7.
Why solids cannot be compressed like gases?
Q 8.
How matter is classified in terms of physical state?
Q 9.
What is evaporation? Why does evaporation cause cooling?
Q 10.
List any five physical properties of liquids.
Q 11.
What do you mean by the following terms:
a. Evaporation
b. Sublimation
c. Condensation
Q 12.
What do you mean by the term Volume?
Q 13.
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 14.
Arrange the following substances in increasing order of intermolecular force of attraction: water, sugar, oxygen
Q 16.
What are the ways a gas can be liquefied?
Q 17.
Define Latent Heat of Fusion and Latent Heat of vaporisation.
Q 18.
Define evaporation.
Q 19.
Define transpiration.
Q 20.
How matter is classified in terms of composition?
Q 21.
Our own bodies contain examples of all three states of matter. Can you identify these?
Q 22.
What is the physical state of water at the following temperatures? (a) 25 °C (b) 0 °C (c) 100 °C
Q 23.
How can matter change its state?
Q 24.
What are the differences between boiling and evaporation?
Q 25.
Why do diffusion become faster at higher temperatures?
Q 26.
Which of the following are matter?
Chair, Air, Love, Smell, Hate, Almonds, Thought, Cold, Cold drinks, Smell of perfume
Q 27.
Convert the following temperature to Celsius scale: (a) 300 K (b) 573 K
Q 28.
Explain compressibility in gases with an example?
Q 29.
Why does the temperature of a substance remain constant during melting and boiling even when heat is being supplied to it continuously?
Q 30.
In which case evaporation of water will be faster i.e. near the sea or far away from the sea.
Q 31.
What are the characteristics of matter?
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.
Why do gases diffuse rapidly?
Q 36.
Which of the following state does not exist at room temperature conditions: a) Solids b) Liquids c) Gas d) Plasma
Q 37.
Why is ice at 273 K more effective in cooling than water at the same temperature?
Q 38.
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 39.
What is the (a) common unit of temperature, and (b) SI unit of temperature ?
Q 40.
Write the relation between Kelvin scale and Celsius scale of temperature.
Q 41.
State whether the following statement is true or false : Solid carbon dioxide is stored under low pressure.
Q 42.
What are the conditions for 'something' to be called 'matter' ?
Q 43.
Convert the temperature of 573 K to the Celsius scale.
Q 44.
Why do solids expand a bit on heating and contract a bit on cooling?
Q 45.
The boiling point of water is 100°C. Express this in SI units (Kelvin scale).
Q 46.
(a) What is evaporation ? State the various factors which affect evaporation.
Why does evaporation cool a liquid ?
Q 47.
Honey is more viscous than water. Can you suggest why ?
Q 48.
Define boiling. Why boiling is considered as a bulk phenomenon?
Q 49.
What causes evaporation?
OR
Explain evaporation and its cooling effect in terms of kinetic energy of particles.
Q 50.
Write the full forms of the following :(a) LPG (b) CNG
