(i) It is a process of changing liquid sinto vapour.
(i) It is a process of changing liquids into vapour.
(ii) Molecules of liquids escape from all parts of the liquids into atmosphere.
Molecules of liquids escape from upper surface of the liquid into atmosphere.
(iii) It is a fast process.
(iii) It is a slow process.
(iv) It takes place only at a fixed temperature called boiling point.
(iv) It takes place at all temperature, even at melting point.
(v) In boiling, the vapour pressure of liquids is equal to the atmospheric
(v) In evaporation the vapour pressure of liquid is less than the atmospheric
Tuesday, March 29, 2011
MATTER in our surrounding solved questions
CBSE ADDA Matter in our surrounding solved questions
Q. 1. What is a matter?
Anything that occupies space and has mass is called a matter.
For example:- Chalk, Milk, Sugar etc.
Q. 2. Sodium chloride and sugar have same appearance. Are they same or different?
They have different physical and chemical properties. So, they are different
Q. 3. All substances around us are alike. How?
All substances can occupy space and have weight.
Q. 4. How can we say that air is a matter?
Air occupies space and have weight. Hence air is a matter.
Q. 5. State the characteristics of matter?
Matter has mass, weight and occupies space.
Q. 6. What are the intensive properties of matter?
Density, colour, melting point, boiling point, refractive index etc. are the intensive properties of matter as it does not depend upon the amount of matter contained in it
Q. 7. What are the extensive properties of matter?
The properties which depends upon the amount of matter contained in a substance is called extensive properties of matter. For example mass, weight, volume, energy etc.
Q. 8. State the characteristics of particles of matter.
(i) There is enough space between the particles of matter.
(ii) The particles of matter are continuously moving about their mean position.
(iii) The particles of matter attract each other.
Q. 9. What is the effect of temperature on a matter?
Particles of matter posses kinetic energy. As the temperature rises, kinetic energy increases.
Q. 10. The smell of hot sizzling food reaches us several metres away. Why?
As the rate of diffusion increases with the increase in temperature.
Q. 11. What is diffusion?
When two gases are mixed, their molecules mix with each other due to their speed and random motion. This phenomenon is known as diffusion
Q. 12. If a bottle of perfume is opened in one corner of a room, it immediately spreads throughout the room. Why?
The molecules of a gas are free to move in a chaotic motion at a greater speed throughout the vessel in which it is contained. When the bottle of perfume is opened in one corner of the room, the molecules of perfume move at random motion in all direction and mix with the molecules of air and reaches us
Q. 13. Name the three states of matter with examples.
The three states of matter are:
(i) Solid: - A solid has definite shape and volume.Example – wood, metal, rubber.
(ii) Liquid: - A liquid has definite volume and its shape is the shape of the container.Example – water, oil, petrol.
(iii) Gas: – A gas has neither a definite volume nor a definite shape. Example – air, hydrogen, oxygen.
Q. 14. State the characteristics of solids.
Solids are rigid. The molecules of solids are packed closely and remain fixed at their position. The molecules of solids are packed closely and remain fixed at their position. The force of attraction between the molecules are very strong and hence they resist any change in their shape or volume.
Q. 15. What are the characteristics of liquids?
Liquids have definite volume but not a definite shape. They take the shape of a container in which they are stored. The molecules have weaker force of attraction than solids, and hence can flow easily.
Q. 16. What are the characteristics of gases?
Gases have neither definite volume nor definite shape. The molecules have very weak force of attraction and low density. They can be compressed to liquid state and flow in any direction.
Q. 17. What are fluids?
Substances having tendency to flow are called fluids. Liquids and gases are fluids.
Q. 18. Give one similarity between a liquid and a gas and one dissimilarity.
Similarity: - Both liquids and gases are fluids and they take the shape of the container.
Dissimilarity: - A gas can be compressed easily to a desired volume. A liquid can not be compressed easily. A small volume of gas occupies the whole space of the container. But the volume of liquid is fixed. A large volume of gas can be stored in a container of very small volume.
Q. 20. What property of gas is utilized when natural gas is supplied for vehicles.
High compressibility of gas is utilized and compressed it for supply for the vehicles in the name of CNG.
Q. 21. What are ‘intermolecular forces’? How are these related to the three states of matter ?
The force operating between the atoms or molecules of a matter is called intermolecular force. The intermolecular force in solid are strong. This keeps the constituent particles very close to each other. Due to this solids are rigid and incompressible. This also give ordered arrangement of the particles giving regular geometrical shape to the solid.
In liquid, intermolecular force is weak to give definite shape.
In gas, intermolecular force is negligible and so its constituents particles are free to move and occupy the available space.
Q. 22. Separate the following substances in groups of high and low intermolecular force:Ice, sulphur vapour, nitrogen, sugar, copper, air, salt, plastic.
High intermolecular forces :- Ice, sugar, copper, salt, plastic
Low intermolecular forces :- Sulphur vapour, nitrogen, air
Q. 23. Which of the following substances you expect strongest and in which weakest intermolecular force:
Water, alcohol, sugar, sodium chloride, carbon dioxide.
Sodium chloride – Strongest
Carbon dioxide – Weakest
Q. 24. Why are gases compressible but liquids not ?
The molecules of a gas are separated very far and there is a lot of empty space between them. Hence gases can be compressed easily. In liquids molecules are closer to each other and can be brought further closer only under very high pressure.
Q. 25. How does the state of matter changes from solid to liquid and then to gas on heating ?
In solids particles are very close. When heat is given to solid, the distance between particles increases and it takes the shape of the container. On further heating the distance between the particles increases in such an extent that the molecules are free to move. This is a gaseous state.
Q. 26. How is pressure developed in a container full of a gas ?
Gaseous molecules are free to move in the container. The molecules collide with each other and with the wall of the container. On the wall the molecules exert force. The force per unit area is called the pressure of the gas.
Q. 27. What are the applications of interconversion of states of matter ?
The interconversion of states of matter is used to :
(i) generate electricity in thermal power plant.(ii) separate nitrogen and oxygen from air by liquefaction.
(iii) prepare machine parts.(iv) prepare room fresheners.(v) prepare ice-creams.
Q.28. What happens to a gas if its intermolecular space is reduced ?
If the intermolecular distance between molecules of a gas is reduced, it changes to liquid. Further reduction it is changed to solid.
Q. 29. Which of the following substances is most compressible?CO2, H2O, NaCl.--------------------àCO2
Q. 30. Which property of a gas results in steady pressure of the gas ?
The constant bombardment of the gas molecules with the walls of the container
Q. 31. In which of the following substances, weakest intermolecular force is expected:H2O, CH3OH, Al, He.
Q. 32. One gas mixes with another gas easily. What is this property called ?
Q. 33. Describe briefly (i) Melting point and (ii) Boiling point.
(i) Melting point :- The melting point of a solid is that temperature at which it changes into the liquid. From the beginning to the end of melting, the temperature does not change.
(ii) Boiling point :- The boiling point of a liquid is that temperature at which a liquid starts boiling at the atmospheric pressure.
Q. 34. How would you find out whether a sample of sodium chloride is pure or impure ?
Pure substance melts at its melting point. If sodium chloride melts at 97ºC,then the sample is pure otherwise impure.
Q. 35. How will you find out whether a sample of water is pure or impure ?
The boiling point of water at one atmospheric pressure is 100ºC. If the given sample of water boils at 100ºC then it is pure otherwise impure.
Q. 36. Why do solids have a fixed shape and gases have neither a fixed shape nor a fixed volume ?
In solids the molecules are close due to intermolecular force. The molecules are arranged in a fixed pattern. The movement of molecules are not possible. Hence its shape are fixed . In gases the intermolecular force are negligible. Molecules are free to move in any direction. The distance between the molecules is very large. Hence gases do not have fixed shape and fixes volume.
Q. 37. What is Vaporization ?
The change of liquid into its gaseous form (vapour) when temperature of liquid is increased is called vaporization.
Q. 38. What is Sublimation ?
A change of state directly from solid to gas without changing into liquid state or vice-versa is called sublimation.
Q. 39. What is Condensation ?
A change of gaseous state to liquid state or solid state is called condensation.
Q. 40. What is Deposition ?
A change of vapour to solid is called deposition. It is the reverse process of sublimation
Q. 41. What is Liquefaction ?
A substance which is gas in normal condition, when changed to liquid by cooling it under pressure is called liquefaction.
Q. 42. What is Solidification ?
A substance which is a liquid in normal condition, when changed to solid to by cooling it under pressure is called solidification.
Q. 43. What is difference between vapour and gas.
Vapour is used to denote the gaseous state of fluids which exists as liquids under normal conditions, while gas is used to denote the gaseous state at normal temperature. We always speak water vapour and carbon dioxide gas.
Q. 44. Why do the three states of matter differ ?
The three states of matter differ due to :
(i) Difference in packing and arrangement of molecules in the three states.
(ii) Intermolecular force of attraction are different in the three states.
Q. 45. Why does the temperature remain constant until whole of the solid changes into liquid, though the heat energy is constantly supplied ?
During melting, temperature of the liquid phase remains the same as that of the liquid phase. The heat energy supplied is utilized to destroy the crystal pattern and is stored in the liquid phase as potential energy.
Q. 46. Why does the temperature remain constant during boiling though heat is constantly supplied ?
The heat energy supplied is utilized to destroy the intermolecular force amongst the molecules of the liquid and is stored as potential energy.
Q. 47. Why does a gas fill a vessel completely ?
The molecules of a gas are moving continuously with a high speed in all direction and intermolecular force amongst the molecules are negligible. Hence it fills the vessel completely.
Q. 48. Compare the process of boiling and vaporization.
Q. 49. Explain the term boiling on the basis of kinetic theory of gases.
When a liquid is heated up to its boiling point, the heat is absorbed by the molecules and stored in the form of potential energy . When potential energy of the molecule is is increased, the intermolecular distance is increased. It means intermolecular force of attraction reduces to zero. The molecules start escaping in air causing the liquid to boil.
Q. 50. Explain the term melting on the basis of kinetic theory.
The molecules of solids vibrate about its mean position. When it is heated, its kinetic energy is increased and it starts vibrating vigorously. At the melting point the intermolecular force of attraction is reduced and particles can not hold each other with strong force to hold them in their fixed position. The crystalline structure is destroyed and it starts melting.