Chapter 1 MATTER IN OUR SURROUNDINGS
MULTIPLE CHOICE QUESTIONS .
1. Liquids have
a ) fixed volume and fixed shape
b ) fixed shape and no fixed volume
c ) fixed volume and no fixed shape
d ) neither fixed volume not fixed shape .
2. Materials existing as liquids have
a ) boiling point and melting point above room temperature
b ) boiling point and melting point are below room temperature
c ) boiling point above room temperature and melting point below room temperature
d ) boiling point and melting point below room temperature .
3. Intermolecular force of attraction is maximum in
a ) solids b ) liquids c ) gases d ) plasma particles
4. When we add sugar particles to water , particles of sugar disappear because they
a ) are very small b ) get into the space between water particles
c ) are moving d ) are colourless
5. Which of the following pairs will not exhibit diffusion ?
a ) oxygen and water
b ) sugar crystals and water
c ) hydrogen and oxygen
d ) salt and sand
6. Which one of the following properties is not a characteristic of liquids ?
a ) Fluidity b) Definite shape
c) Definite volume d) Compressibility
7. Large volume of compressed natural gas is available in small cylinders due to its property of
a ) high inflamability b ) easy availability
c ) high compressibility d ) low density
8. Gases are liquefied under
a ) high pressure , high temperature
b ) high pressure , low temperature .
c ) low pressure , high temperature
d ) low pressure , low temperature
9. Which one of the following changes represent sublimation ?
a ) solid to liquid
b ) solid to gas
c ) solid to liquid then liquid to gas
d ) liquid to gas
10. Gases do not have
a ) high compressibility b) high density
c ) high fluidity d ) large volume
11. Evaporation of a material takes place
a ) above its boiling point b) below its boiling point
c ) above its melting point d ) below its melting point
12. Particles of a liquid
a ) are most ordered
b ) move randomly
c ) have large intermolecular spaces
d ) can slip and slide over each other .
13. The fluorescent tubes glow because of
a ) presence of charged particles
b ) high density of gases
c ) high temperature
d ) high applied voltage
14. Which of the following processes does not convert a liquid into vapours ?
a ) Boiling b ) heating
c ) evaporation d ) condensation
15. Which of the following decreases the rate of evaporation ?
a ) more surface area b ) high humidity
c ) high temperature d ) speedy wind
16. Which of the following combination gives almost negligible diffusion ?
a ) solid - solid b ) solid - liquid
c ) liquid - liquid d ) gas - gas
17. Gases can easily compressed because they have least intermolecular force of attraction .
a ) assertion is correct and reason is correct
b ) assertion is correct and reason is wrong
c ) assertion is wrong and reason is correct
d ) assertion is wrong and reason is wrong
FILL IN THE BLANKS
1. The intermixing of particles of two substances on their own is known as Diffusion
2. The mass per unit volume of a substance is called Density
3. The Melting point of a solid is an indication of the strength of intermolecular forces .
4. The amount of heat given to a substance during melting or boiling at constant temperature disappears as latent heat
5. The reduction in temperature and increase of pressure can liquefy gases.
6. Rate of evaporation increases with surface of the vessel
7. The state which contains ionized energetic particles Plasma
8. The state of matter which can form heaps and have boundaries Solid.
ONE MARK QUESTIONS
1. What is the Physical nature of matter ?
Physically matter is Particulate i.e. made up of particles
2. Define Matter .
Anything that occupies space , possess mass and can be felt by someone .
3. Early Indian philosophers classified matter in the form of five basic elements ( Panchatatva ) . Which were they ?
Air , Earth , Fire , Sky and Water .
4. Define
Melting or fusion : The change of state from solid to liquid is called melting or fusion .
Melting point : The temperature at which a solid charges into liquid at atmospheric pressure is called melting point . Eg .: melting point of ice is 0 ° C or 273.16K
Latent heat of fusion : The amount of heat required to convert 1 Kg of a solid into liquid at atmospheric pressure at its melting point is known as latent heat of fusion .
Vapourisation : The change of state from liquid to gas .
Boiling point : The temperature at which a liquid starts boiling at atmospheric pressure .
Latent heat of vaporization : The amount of heat energy required to convert 1 kg of a liquid into gas at atmospheric pressure at its boiling point .
Vapour : A substance in gaseous state at a temperature lower than it's critical temperature is known as vapour . Eg .: water vapour , sodium vapour
Diffusion : Intermixing of particles of two or more substance on their own is diffusion .
Liquefaction point : The constant temperature at which a gas rapidly changes into its liquid state by giving out heat energy is liquefaction point .
Freezing : The change of state from liquid to solid .
Condensation : The change of state from gas to liquid . It is also a reverse process of vaporization .
Sublimation : It is the phenomenon in which a solid substance directly changes into gaseous state or vice versa without being changed into liquid state .
Atmospheric pressure : The pressure exerted by atmospheric air is called atmospheric pressure .
Evaporation : The phenomenon of change of a liquid into vapour at any temperature below its boiling point .
5 . Why a rubber band being a solid can change its shape ?
Rubber band can change its shape by stretching or expanding due to property of elasticity when force is applied .
6 . Solid carbon dioxide ( dry ice ) is stored under high pressure . Why ?
It is because solid carbon dioxide on decreasing pressure gets converted into gaseous carbon dioxide .
7. Sponge being a solid can be compressed . Why ?
This is because sponge contains numerous pores in which air is filled , when it is pressed , air expels out , and thus can be compressed
8. Suggest two methods to liquefy atmospheric gas .
a ) Reducing Temperature
b ) Applying Pressure
9. How are kinetic energy and temperature related ?
Kinetic Energy is directly proportional to temperature .
Equation : KE∞ T
10. Cloths dry faster on a windy day .
With an increase of wind speed , the particles of matter move away with wind and thus cloths dry faster .
11. What is dry ice ?
Solid carbon - di - oxide is called dry ice . It is stored under high pressure . It's chemical formula is solid CO2 .
12. Why does our palm feel cold when we Acetone / perfumes / petrol on it ?
This is because the particles of acetone / perfumes / petrol gain energy from our palm and evaporates , causing palm to feel cold . put some
13. After shower , your bathroom mirror is covered with water . Why ?
This is because the rising of water vapour from hot water condenses when it touches the mirror ( cold ) .
TWO MARKS QUESTIONS
1. Arrange these in increasing order of their force of attraction : water , sugar , oxygen .
Oxygen ( gas ) , water ( liquid ) and sugar ( solid ) The force of attraction is weakest in gases followed by liquids and strongest in solids . Oxygen < water < sugar
2. What are the characteristics of particles of matter ?
i ) There are spaces between particles of matter
ii ) The particles of matter are continuously moving
iii ) Particles of matter are attracted to each other .
3 . A wooden table should be called as a solid . Why ?
A wooden table has definite shape and volume . It can't be compressed , due to this property it is considered as solid .
4. How will you show that particles of matter have space between them ?
Take a beaker half - filled with water . Mark the level of water . Now add some sugar in it . Now the added matter disappears and there is hardly any change in the level of water . It is because of particles of one matter i.e. sugar get into the spaces between the particles of the other matter i.e. water . So we can say that there is enough space between them .
5. Give one similarity and one dissimilarity between a liquid and a gas .
Similarity Both liquids and gases are fluids and assume the shape of the container .
Dissimilarity : A gas can be compressed easily where as a liquid cannot .
6. Why liquids and gases are called fluids ?
Liquids and gases have tendency to flow . Liquid can flow from higher level to lower level . The gas flow in all directions . Due to this nature of flowing , both of them are called fluids .
7. How does diffusion help aquatic plants & anim s ?
Atmospheric oxygen and carbon dioxided get diffuse in water . Aquatic plants take dissolved CO2 for photosynthesisfor survival . Aquatic plants and animals can breathe under water with the help of dissolved oxygen . Thus , diffusion of gases help aquatic plants and animals to survive .
8. Mention the factors which increase the rate of evaporation .
i ) Increase in surface area
ii ) Increase in temperature
iii ) Increase in wind
iv ) Decrease in humidity
9. How does water kept in earthen pot become cool in summer ?
There are small pores in the walls of the earthen pot through which water evaporates . The energy needed for evaporation is taken from water in the pot . As a result water kept in a pot becomes cool in summer .
10. What is meant by diffusion ? Explain with an example .
Intermixing of particles of two substances on their own is called diffusion or movement of particles from region of higher concentration to the region of lower concentration is called diffusion .
Eg.: Light an agarbatti in one corner of the room and stand in the other corner . Very soon , you will feel smell of agarbatti . The particles of agarbatti mix with the particles of air and spread out eventually and reach to us even at a distance . This is due to diffusion of agarbatti particles into particles of air .
11. How does rate of diffusion change with a ) Density of liquid and b ) Temperature ?
a ) Rate of diffusion decreases with density of a liquid . Honey is denser than ink . If you add a drop of ink and honey in two separate jars space filled with water , it will be observed that honey takes longer time to reach the bottom of the jar as compared to that taken by ink .
b ) Diffusion increases with rise of temperature . For eg.:Liquid mix faster at higher temperature .
12. Water as ice has a cooling effect , whereas water as steam may cause severe burns . Explain this observation .
In case of ice , the water molecules have low energy while in the case of steam the water molecules have high energy . The high energy of water molecules in steam is transported as heat and may cause burns on the other hand in case of ice the water molecules take energy from the body and thus give a cooling effect .
13. Convert these temperature to Celsius scale . i ) 300 K ii ) 573 K
i ) 300-273 = 27 ° C
ii ) 573-273 = 300⁰ C
14. Convert these temperature to Kelvin scale i ) 25 ° C ii ) 379 ° C
i ) 25+ 273 = 298K
ii ) 379 +273 = 652K
15. Write a note on plasma
Plasma: It is the fourth state of matter , which is formed at extremely high temperature and consists of charged ions . These particles are present in the form of ionized gases .
16. We can get smell of perfume sitting several meter away . Why ?
This is due to diffusion . The particles of perfume intermix with the particles of air and the smell of the perfume reaches us sitting several meters away .
17. Why are we able to sip hot milk faster from a saucer rather than from a cup ?
The surface area of milk in a cup is small so evaporation occurs slowly . Hence milk in a cup remains hot for a long period of time . However when milk is placed in a saucer , the surface area of milk is more as a result evaporation occurs faster and milk cools more quickly in saucer .
18. Why does the temperature of a substance remain constant during its melting point or boiling point ?
The temperature of a substance remains constant at its melting point and boiling points until all the substances melt or boils because , the heat supplied is continuously used up in changing the state of the substance by overcoming the forces of attraction b / w the particles . This heat energy absorbed without showing any rise in temperature is given the name latent heat of fusion / latent heat of vaporization .
19. Gas fills completely the vessel in which it is kept . Why ?
This is because the particles of gas are loosely packed . The force of attraction between them very less and kinetic energy of particles is very high due to which the particles move randomly filling the entire space available in the vessel .
20. Gas exerts pressure on the walls of the container . Why ?
In gaseous state , the particles move about randomly at high speed . Due to this the particles collide with each other and also the walls of the container . Thus gas exerts pressure on the wall of the container .
21. Why is solid CO2 called dry ice ?
Solid CO2 gets converted directly to gaseous state on decreasing pressure to one atmospheric pressure without changing to liquid . So , solid CO₂ does not wet the surface on which it is kept . Hence it is called dry ice .
22. Why does desert cooler ( air cooler ) cool better on hot dry day ?
On a hot dry day , temperature is high and humidity is low . Both these factors increase the rate of evaporation and thus enormous cooling is produced .
23. Naphthalene balls disappear in time without leaving any residue . Why ?
Naphthalene ball is a volatile solid . It undergoes sublimation at room temperature , as a result solid naphthalene ball converts into vapour and become a part of air around us . Therefore leaving no residue .
24. When a player gets injured in a game Ethyl Chloride is sprayed on the injured part . Why ?
Boiling point of Ethyl Chloride is very low . Hence it evaporates quickly by absorbing body temperature . By losing heat , temperature of skin becomes so low i.e. almost it becomes numb . Due to this numbness the player does not feel pain .
25. Give reasons for the following a ) Water at room temperature is a liquid b ) An iron Almirah is a solid at room temperature
a ) Because room temperature is between 20 ° C to 35 ° C , at this temperature naturally water exist in liquid form .
b ) Because it has a fixed shape , size , volume and It is rigid at room temperature .
26. Liquids generally have lower density as compared to solids , but you must have observed ice floats on water . Why ?
When we compare the density of ice and water even though ice is in solid state its density is less than water because of the arrangement of water molecules with more intermolecular spaces . Hence , ice has lesser density and floats on water .
LONG ANSWERS QUESTIONS
1. Write the unit of symbol of the given physic aquantity
Quantity Unit Symbol
Temperature Kelvin K
Length meter m
Mass kilogram Kg
Weight newton N
Volume cubic m³
Density meter per cubic meter Kgm - ³
Pressure pascal Pa
2. Explain sublimation , Along with a neat diagram.
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Take some powered ammonium chloride in a china dish , and crush it . Put an inverted funnel over the china dish put a cotton plug or glass wood plug on the stem of the funnel as shown in fig . Ammonium chloride directly changes into vapours . Vapours , coming in contact with corner sides of the funnel undergo deposition in the form of white powder .
Here we observe that there is a change of state directly from solid to gas without changing into liquid . This is sublimation .
3. Write the differences between boiling and evaporation
Boiling
> It takes place at higher temperature
> It is a bulk phenomenon
> Does not cause cooling
Evaporation
> It takes place at room temperature
> It is a surface phenomenon .
> It causes cooling
4. Comment on the following statements.
i ) Evaporation produces cooling
ii ) Rate of evaporation in an aqueous solution .
iii ) Though sponge can be compressed it is considered a solid .
( i ) Evaporation produces cooling as the particles at the surface of the liquid gain energy from the surroundings and change into vapour , there by producing a cooling effect .
( ii ) Air around us can't hold more than a definite amount of water vapour at a given temperature which is known as humidity . So if the air is already rich in water vapour , it will not take up more water . Rate of evaporation of water will decreases .
( iii ) A sponge has minute holes / pores in which air is trapped . Also the material is not rigid when we press it , the air is expelled out and are able to compress it .
5. Write the difference between States of matter and their difference
a) Solid b) Liquid c) Gas
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