AP 9th Class Physics 1st Lesson Questions and Answers Matter in Our Surroundings

AP State Board new syllabus AP Board Solutions Class 9 Physics 1st Lesson Matter in Our Surroundings Questions and Answers.

AP 9th Class Physical Science 1st Lesson Questions and Answers Matter in Our Surroundings

9th Class Physics 1st Lesson Matter in Our Surroundings Questions and Answers (Exercise)

Question 1.
Convert the following temperatures to the celsius scale.
a) 293K
b) 470K
Answer:
Kelvin to Celsius:
a) 293 K to C
K = C+273
C = K – 273= 293 – 273
293K = 20°C

b) 470 K to C
K = C + 273
C = K- 273= 470 – 273
470K = 197°C

Question 2.
Convert the following temperatures to the kelvin scale.
a) 25°C
b) 373°C
Answer:
a) 25°C to K
K – C + 273
= 25 + 273
25°C = 298 K

b) 373 °C to K
K = C + 273
= 373 + 273
373°C = 646 K

Question 3.
Give reason for the following observations.
a) Naphthalene balls disappear with time without leaving any solid.
b) We can get the smell of perfume sitting several metres away.
Answer:
a) Naphthalene balls undergo sublimation i.e., naphthalene transforms from solid state to vapour state without coming into liquid state.
b) Molecules of perfume diffuse faster in the air and reaches several metres away.

Question 4.
Arrange the following substances in increasing order of forces of attraction between the particles – water, sugar, oxygen.
Answer:
Oxygen – Water – Sugar.

Question 5.
What is the physical state of water at
a) 25° C
b) 0° C
c) 100° C?
Answer:
a) at 25° C water is in liquid state.
b) at 0° C water exist in both solid state and liquid state.
c) at 100° C water exist in both liquid state and vapour state.

Question 6.
Give two reasons to justify –
a) water at room temperature is a liquid.
b) an iron almirah is a solid at room temperature.
Answer:
a) water is liquid at room temperature :

• Intermolecular space is very large.
• Intermolecular force is very less due to this water is a liquid.

b) an iron almirah is a solid at room temperature :

• Intermolecular force is very high.
• Intermolecular space is very less due to this Iron almirah is a solid at room temperature.

Question 7.
Why is ice at 273 K more effective in cooling than water at the same temperature ?
Answer:
Ice at 273 K need heat energy (latent heat of fusion) to convert into water.
Whereas water at 273 K doesn’t need any heat energy, so ice at 273 K is more effective in cooling as it takes more surface temperature.

Question 8.
What produces more severe burns, boiling water or steam ?
Answer:
Steam doesn’t need any heat energy (latent heat of vaporisation) whereas boiling water at the same temperature need energy, so steam causes more severe burns.
Specific heat of steam is (2260 KJ/kg).

Question 9.
Name A, B, C, D, E and F in the following diagram showing change in its state.

Answer:
A : Solid changes to liquid by the process of fusion.
B: Liquid changes to gas by the process of vaporisation.
C: Gas changes to liquid by the process of liquefaction (condensation).
D: Liquid state changes to solid by the process of solidification (freezing).
E: Solid changes into gaseous state by the process of sublimation.
F: Gas changes into solid by the process of deposition.

9th Class PS 1st Lesson Questions and Answers (InText)

Question 1.
Which of the following are matter ?
Chair, air, love, smell, hate, almonds, thought, cold, lemon water, smell of perfume.
Answer:
Chair, air, almonds, smell of perfume (with gas), lemon water – Matter.

Question 2.
Give reasons for the following observation :
The smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go close.
Answer:

• Vapours eminating from hot sizzling food has high kinetic energy.
• Due to this it reaches several metres away.
• Whereas cold food doesn’t eminate any vapours to smell it we have to go near to it.

Question 3.
A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
Answer:

• The intermolecular force is less and intermolecular space is more in water.
• That’s why he was able to cut through the water.

Question 4.
What are the characteristics of the particles of matter?
Answer:
Characteristics of the particles of matter :

• All matter is made up of tiny particles.
• Particles of matter have spaces between them.
• Particles of matter move continuously.
• Particles of matter attract each other.

Question 5.
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.
Answer:
Exhaust from chimneys, air, cotton, water, honey, chalk and iron.

Question 6.
a) Tabulate the differences In the characteristics of states of matter.
b) Comment upon the following: rigidity, compressibility, fluidity, fifing a gas container, shape, kinetic energy and density. . . .
Answer:
a)

Characteristics	Solids	Liquids	Gases
Shape	Definite shape	No definite shape	No definite shape
Volume	Fixed volume	Fixed volume	No fixed volume
Density	Very high	Lower than solids	Lower than solids & liquids
Compressibility	Very less	Very less	Very high
Rigidity	High	Very less	Not rigid
Fluidity	Don’t flow	Flow from high to low	Flow in any direction
Filling a gas container	Don’t need a container	Need a container	Need a container
Kinetic energy	Least	More than solids	More than solids & liquids

b)

• Rigidity: The tendency of a substance to retain/maintain their shape when subjected to outside force.
• Compressibility: The matter has intermolecular space. The external force applied on the matter can bring these particles closer. This property is called compressibility. Gases and liquids are compressible.
• fluidity: The tendency of particles to flow is called fluidity. Liquids and gases flow.
• Filling of a gas container: Gases have particles which vibrate randomly in all the directions. The gas can fill the container.
• Shape: Solids have maximum intermolecular force and definite shape. Whereas liquids and gases takes the shape of container.
• Kinetic energy: The energy possessed by particles due to their motion is called kinetic energy. Molecules of gases vibrate randomly as they have maximum kinetic energy.
• Density: It is defined as mass per unit volume, the solids have highest density.

Question 7.
Give reasons.
a) A gas fills completely the vessel in which ills kept.
Answer:
Molecules of gas has a large intermolecular space and high kinetic energy due to this they completely fill the vessel of the container.

b) A gas exerts pressure on the walls of the container.
Answer:
Due to high kinetic energy particles of gas move and hit the walls of the container and exert pressure.

c) A wooden table should be called a solid.
Answer:
It has a definite shape and volume, so wooden table is a solid.

d) We can easily move our hand in air but to do the same through a solid block of wood we need a karate expert.
Answer:
The molecules of air has less intermolecular force and more intermolecular space, so we can move our hand freely.
Wood is a solid its intermolecular force is very high and has less space, so we can’t move our hand through it.

Question 8.
Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why.
Answer:

• Volume of water increases when it becomes ice, so it becomes less denser than water. So it floats.
• During the formation of ice air particles gets trapped inside it, this makes it less denser than water, so it floats on water even though it is solid.

Question 9.
Convert the following temperature to celsius scale:
a. 300K b. 573K
Answer:
Relation between celsius and kelvin scale of temperature K = C + 273.
a) 300 K to C
C= K – 273
300 – 273 = 27°C

b) 573 K to C
C= K – 273
573 – 273 = 3°C

Question 10.
What is the physical state of water at :
a) 250°C
b) 100°C ?
Answer:
a) at 250°C water is in vapour state (steam).
b) at 100°C water is in liquid state.

Question 11.
For any substance, why does the temperature remain constant during the change of state?
Answer:

• During the change of state heat energy is used to over the intermolecular force of attraction between the particles.
• Due to this particles absorb heat hence there will no change in temperature.

Question 12.
Suggest a method to liquefy atmospheric gases.
Answer:
We can liquefy gases by

• increasing the pressure.
• decreasing the temperature.

Question 13.
Why does a desert cooler cool better on a hot dry day?
Answer:

• Desert cooler contains wood – pads around it.
• The circulating water in the cooler wets the pads.
• The hot & dry air passes through these wet pads.
• The water droplets takes the temperature from air and evaporates.
• Evaporation brings cooling.
• So, the cooled air is pushed out.

Question 14.
How does the water kept in an earthen pot (matka) become cool during summer?
Answer:

• Earthen pot (matka) contains tiny pores.
• The water molecules seeps through the pores into outer surface.
• By taking the temperature from bulk of the liquid they evaporate, causing cooling.

Question 15.
Why does our palm feel cold when we put some acetone or petrol or perfume on it?
Answer:

• When petrol (or) perfume sprayed on hand.
• It has low boiling point, so it takes the temperature of the hand and evaporates.
• Which causes cooling on our palm.

Question 16.
Why are we able to sip hot tea or milk faster from a saucer rather than a cup ?
Answer:

• Saucer has a greater surface area than a cup.
• Greater surface area quicker the evaporation.
• Due to this it is easier to sip on a saucer than a cup.

Question 17.
What type of clothes should we wear in summer.?
Answer:

• We should wear cotton clothes in summer.
• Cotton is a good absorber of sweat.
• Which gets evaporated through pores and brings cooling.

9th Class Physical Science Chapter 1 Questions and Answers (Lab Activities)

(Page No. 2) Activity 1.1

Question 1.
How do you prove that matter is made up of particles?
Answer:
Procedure:

• Take a 100 ml beaker.
• Fill half the beaker with water and mark the level of water.
• Dissolve some salt/sugar with the help of a glass rod.
• Observe any change in water level.

Observations:

1. What do you think has happened to the salt?
Answer:
The salt particles dissolves in water.

2. Where does it disappear?
Answer:
The salt particles Intermix between spaces of water particles.

3. Does the level of water change?
Answer:
No, the Level of water does not change.

(Page No. 2) Activity 1.2

Question 2.
How do you prove that the particles of matter are very small?
Answer:
Procedure :

• Take 2-3 crystals of potassium permanganate and dissolve them in 100 ml of water.
• Take out approximately 10m of this solution and put it into 90m of clear water.
• Take out 10m of this solution and put it into another 90m of clear water.
• Keep diluting the solution like this 5 to 8 times.

Observation :

Is the water still coloured?
Answer:
Yes, the water colour (purple) remains even after repeated dilution.

(Page No. 4) Activity 1.3

Question 3.
How do you prove that particles of matter are continuously moving?
Answer:
Procedure :

• Put an unlit incense stick in a corner of your class.
• Now light the incense stick.

Observations :

1. How close do you have to go near it so as to get its smell?
Answer: We have to go close to smell the unlit incense stick.

2. What happens? Do you get the smell sitting at a distance?
Answer: The smell of lightened incense stick can be felt a long distance.

3. Record your observations.
Answer: Gases diffused faster.

(Page No. 4) Activity 1.4

Question 4.
How do you prove that particles of matter are continuously moving ?
Answer:
Procedure :

• Take two glasses / beakers filled with water.
• Put a drop of blue or red ink slowly and carefully along the sides of the first beaker and honey in the same way in the second beaker.
• Leave them undisturbed in your house or in a corner of the class.

Observations :

1. What do you observe immediately after adding the ink drop?
Answer: The ink spreads in water immediately.

2. What do you observe immediately after adding a drop of honey?
Answer: The honey mixes in water slowly.

3. How many hours or days does it take for the colour of ink to spread evenly throughout the water?
Answer: Spreading of ink in water happens instantly.

(Page No. 4) Activity 1.5

Question 5.
How do you prove that as temperature rises, the particles of matter move faster?
Answer:
Procedure :

• Drop a crystal of copper sulphate or potassium permanganate into a glass of hot water and another containing cold water.
• Do not stir the solution.
• Allow the crystals to settle at the bottom.

Observations :
1. What do you observe just above the solid crystals in the glass ?
Answer: Solid crystals of CuSO₄ dissolve in water.

2. What happens as time passes ?
Answer: After some time the blue colour appears throughout the water (diffusion take place).

3. What does this suggest about the particles of solid and liquid?
Answer: Solid and liquid particles can intermix with each other.

4. Does the rate of mixing change with temperature? Why and how?
Answer: Yes, the rate of mixing changes with temperature. As we increase the temperature, then rate of mixing will also increases.

(Page No. 6) Activity 1.6

Question 6.
How do you prove that particles of matter have force acting them ?
Answer:

Procedure :

• Play this game in the field – make four groups and form human chains as suggested:
• The first group should hold each other from the back and lock arms like Idu-Mishmi dancers.
• The second group should hold hands to form a human chain.
• The third group should form a chain by touching each other with only their finger tips.
• Now, the fourth group of students should run around and try to break the three human chains one by one into as many small groups as possible.

Observations :
1. Which group was the easiest to break? Why ?
Answer: 3rd  group is the easiest, the students are far away just touching their fingers.

2. If we consider each student as a particle of matter, then in which group the particles help each other with the maximum force?
Answer: 1st group, as they are very close to each other (tightly bonded).

(Page No. 6) Activity 1.7

Question 7.
Write an activity to show that the strength of the force of attraction in particles of matter varies from one kind of matter to another.
Answer:
Procedure :

• Take an iron nail, a piece of chalk and a rubber band.
• Try breaking them by hammering, cutting or stretching.

Observation :
In which of the above three substances do you think the particles are held together with greater force?
Answer:  Iron, it can’t be broken by hammering, cutting and even by stretching.

(Page No. 6) Activity

Question 8.
Write an activity to show that the strength of the force of attraction in particles of matter is varies from one kind of matter to another.
Answer:
Procedure : Take some water in a container, try cutting the surface of water with your fingers.

Observations :
1. Were you able to cut the surface of water?
Answer: No, stream of water can’t be divided.

2. What could be the reason behind the surface of water remaining together?
Answer: Particles of ivater has force of attraction.

(Page No. 8) Activity 1.9

Question 9.
Write an activity to show the properties of solids.
Answer:
Procedure :

• Collect the following articles – a pen, a book, a needle and a piece of wooden stick.
• Sketch the shape of the above articles in your notebook by moving a pencil around them.

Observations :
1. Do all these have a definite shape, distinct boundaries and a fixed volume?
Answer: No. All these have do not a definite shape, distinct boundaries and a fixed volume.

2. What happens if they are hammered, pulled or dropped?
Answer: Shape, size and volumes change.

3. Are these capable of diffusing into each other?
Answer: No, they doesn’t diffuse.

4. Try compressing them by applying force. Are you able to compress them?
Answer: No, they are difficult to compress.

(Page No. 8) Activity 1.10

Question 10.
Write an activity to show the properties of liquids.
Answer:
Procedure :
Collect the following :
a) Water, cooking oil, milk, juice, a cold drink.
b) Containers of different shapes. Put a 50 ml mark on these containers using a measuring cylinder from the laboratory.

Observations :
1. What will happen if these liquids are spilt on the floor?
Answer: They start flowing on the floor.

2. Measure 50 ml of any one liquid and transfer it into different containers one by one. Does the volume remain the same?
Answer: Yes, the volume remains the same.

3. Does the shape of the liquid remain the same?
Answer: No. Shape of liquid changes with the change in container.

4. When you pour the liquid from one container into another, does it flow easily ?
Answer: Yes, liquids flow very easily.

(Page No. 10) Activity 1.11

Question 11.
How do you prove that gases are highly compressible as compared to solids and liquids ?
Answer:

Procedure :

• Take three 100 ml syringes and close their nozzles by rubber corks, as shown in the given figure.
• Remove the pistons from all the syringes.
• Leaving one syringe untouched, fill water in the second and pieces of chalk in the third.
• Insert the pistons back into the syringes. You may apply some vaseline on the pistons before inserting them into the syringes for their smooth movement.
• Now, try to compress the content by pushing the piston in each syringe.

Observations :
1. What do you observe ? In which case was the piston easily pushed in ?
Answer: Piston go easily in the syring in which there is air (1-one).

2. What do you infer from your observations?
Answer: Gases have greater compressibility compared to liquid and solids.

(Page No. 12) Activity 1.12

Question 12.
Write an activity to show the conversion of ice to water and conversion of water to water vapour.
Answer:
Procedure :

• Take about 150 g of ice in a beaker and suspend a laboratory thermometer so that its bulb is in contact with the ice, as in the below figure.
• Start heating the beaker on a low flame. Note the temperature when the ice starts melting.
• Note the temperature when all the ice has converted into water.
• Record your observations for this conversion of solid to liquid state.
• Now, put a glass rod in the beaker and heat while stirring till the water starts boiling.
• Keep a careful eye on the thermometer reading till most of the water has vaporised.
• Record your observations for the conversion of water in the liquid state to the gaseous state.

Observations :

• The ice melts at 0°C (All the ice converts into water at 0°C
• The water starts boiling at 100°C and converts into vapour.

(Page No. 16) Activity 1.13

Question 13.
Write an activity to show the changes of sublimation and deposition.
Answer:
Aim : To separate ammonium chloride from the mixture of ammonium chloride and common salt.
Materials required : China dish, funnel, cotton, ammonium chloride, common salt and stove.

Procedure :

• Take some camphor or ammonium chloride.
• Crush it and put it in a china dish.
• Put an inverted funnel over the china dish.
• Put a cotton plug on the stem of the funnel, as shown in the given figure.
• Now, heat slowly and observe.

Observation :
What do you infer from the above activity ?
Answer:

• Ammonium chloride vapours gets deposited near the mouth of the funnel.
• Ammonium chloride (or) camphor undergoes sublimation.

(Page No. 16) Activity 1.13

Question 13.
Write an activity to show the changes of sublimation and deposition.
Answer:
Aim : To separate ammonium chloride from the mixture of ammonium chloride and common salt.
Materials required : China dish, funnel, cotton, ammonium chloride, common salt and stove.

Procedure :

• Take some camphor or ammonium chloride.
• Crush it and put it in a china dish.
• Put an inverted funnel over the china dish.
• Put a cotton plug on the stem of the funnel, as shown in the given figure.
• Now, heat slowly and observe.

Observation :
What do you infer from the above activity ?
Answer:

• Ammonium chloride vapours gets deposited near the mouth of the funnel.
• Ammonium chloride (or) camphor undergoes sublimation.

(Page No. 18) Activity 1.14

Question 14.
How do you prove that rate of evaporation increases with varies aspects?
Answer:
Procedure :

• Take 5 ml of water in a test tube and keep it near a window or under a fan.
• Take 5 ml of water in an open china dish and keep it near a window or under a fan.
• Take 5 ml of water in an open china dish and keep it inside a cupboard or on a shelf in your class.
• Record the room temperature.
• Record the time or days taken for the evaporation process in the above cases.
• Repeat the above three steps of activity on a rainy day and record your observations.

Observation :
What do you infer about the effect of temperature, surface area and wind velocity (speed) on evaporation?
Answer:
1. Evaporation is faster in the china dish which is kept near window.
2. Rate of evaporation depends on:

• Surface Area
• Temperature
• Windspeed.