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CHEMISTRY
CH-1
CLASS-IX
Matter In Ours Surroundings
Q1) What are the characteristics of particles of matter?
Ans)
1.
2.
3.
The characteristics of particles of matter are:
Have a vacant space between them.
They are always in motion.
There are attractive forces between the particles of matter.
Q2) Arrange the following substance in increasing order of force of attraction between
the particles- water, sugar and oxygen.
Ans) In increasing order- Oxygen < Water <Sugar.
Q3) What are fluids?
Ans) The substance which can flow are called fluids e.g. liquid and gas.
Q4) What is physical state of water at 00C?
Ans) Solid state.
Q5) Define boiling point?
Ans) It is constant temperature at which a liquid changes into gas on heating.
Q6) Convert 1000C to Kelvin temperature?
Ans) 1000C = 100+273=373K.
Q7) Define latent heat of vaporisation?
Ans) It is the heat energy required to change one kg of liquid to gas at atmospheric
pressure and at its boiling point.
Q8) Define latent heat of fusion?
Ans)It is the heat energy required to change one kg of solid into liquid at its melting
point.
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Q9) List the factor which affect evaporation?
Ans) 1.Exposed surface area.
2. Temperature.
3. Humidity in air.
4. Wind speed.
Q10) Why is sponge solid although it can be compressed?
Ans) This is because sponge has minute holes in which there is entrapped air. When it is
pressed, the air is expelled out.
Q11) Rubber band can change its shape, is it solid?
Ans) Rubber band is a solid because it changes its shape under pressure and return to its
original shape.
Q12) What happen when the vacant space between the particles of a liquid decreases?
How is this possible?
Ans) The liquid will change into solid. This is carried out by decreasing the temperature or
cooling the liquid.
Q13) Why do we observe water droplets on the outer surface of glass containing ice cold
water?
Ans) This is because water droplets present in air, on coming in contact with glass Ice cold
water loss energy and get converted into liquid state which appear as water
droplets.
Q14) Why should we wear cotton cloth in summer?
Ans) This is because in summer, we perspire more and cotton being a good absorber of
water, absorbs the sweat and exposes it to the atmosphere for easy evaporation.
Q15) Why does gas fill its container completely?
Ans) The molecules in gas are far apart and are in state of rapid random motion in all
possible direction with very high speeds. They move throughout the container in
which they are put. Thus, a gas fills the container completely.
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Q16) What are the uses of inter conversion of matter?
Ans) Uses are:1. Water is converted into steam by heating. Steam is used to run turbines and
generates electricity.
2. Water can be change into steam as well as ice. Therefore, in nature, ice (or snow),
liquid water and water vapour are available.
Q17) Give difference between boiling and evaporation?
Ans)
Boiling
Evaporation
1. It takes at a fixed
1. It takes place at
temperature
called
temperature.
boiling point of the
liquid.
2. It is fast process.
2. It is slow process.
all
Q18) Give the importance properties on the basis of which the three states of matter can
be distinguished?
Ans) They can be distinguished on the basis of shape, volume, compressibility, number of
free space etc.
Q19) Name the five substances which are solid ,name five substance which are liquid ,
name five substance which are gaseous?
Ans) SOLID:-Iron, copper, silver, gas and wood.
LIQUID:-Water, milk, mercury, kerosene oil, and petrol.
GAS: - Hydrogen, Oxygen, carbon dioxide, nitrogen.
Q20) Give two methods by which a gas can be changed into liquid.
Ans) (I) By decreasing temperature, (II) By increasing pressure
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Q21)SUBLIMATION: The process due to which a solid directly changes into gaseous
state on heating and a gaseous state directly changes into solid state on cooling without
changing into liquid state.
Q22) F ̵ 32/9=C/5
Q23)Light and sound are considered to be matter. why?
Ans) Because they have no mass and do not occupies space.
Q24)What are the characteristics of the particles of matter?
Ans)a.They have space between them.
b.They are always in motion.
c.There are attractive forces between them.
Q25)How do density vary in the three states of matter?
Ans) Gases have very low density, liquids have higher density as compared to gases and
solid have much higher density than liquid.
Q26) How do water kept in an earthen pot (matka) become cool during summer?
Ans) This is because the water comes out from the pores of earthen pot and it
evaporates. Due to evaporation it causes cooling.
Q27)Why does a desert cooler cool better on a hot dry day?
Ans)This i s because on hot dry day ,due to increase is temperature and lesser humidity
the evaporation of water will be faster.
Q28)Why does ours palm feel cold when we put some acetone or petrol or perfume on
it?
Ans)This is because the particles of acetone or petrol or perfume gain energy from ours
palm and surroundings and evaporate causing cooling.
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Q29)Fill in the blanks:
a. There are 3 states of matter.
b. In gases there are large vacant spaces between molecules.
c. Evaporation causes cooling.
d. Gaseous Changes into liquid on decreasing temperature and increasing pressure.
e. Liquids have one free surface.
f. Solid have infinite free surface.
g. Water is liquid at 25oC.
h. Dry ice is solid carbon dioxide.
i. The molecules of a solid are closely packed.
j. Liquid state is in between solid a gaseous state.
Q30) Name the phenomena which causes the following change.
a. Wax change to liquid in the hot sun- Fusion.
b. Disappearance of naphthalene balls- sublimation.
c. Drying of wet cloths-evaporation.
d. Formation of clouds – condensation.
e. Formation of snow- solidification.
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