CHAPTER 2 IS MATTER AROUND US PURE

What is a Mixture?

Mixtures are constituted by more than one kind of pure form of matter.

Type of mixtures-

Homogeneous Mixture	Heterogeneous Mixture
Composition is uniform throughout	Composition is not uniform
Components are not visible separately	Components are visible separately
Appears as a single phase	Appears as two or more phases
Same properties at every point	Different properties at different points
Particles are evenly mixed	Particles are unevenly mixed
Example: salt solution, sugar in water, air	Example: oil and water, sand in water, soil

✨ One-line trick to remember:

• Homogeneous = “Same everywhere”

Heterogeneous = “Different at different places

What is a Solution?

A solution is a homogeneous mixture of two or more substances.

Alloys: Alloys are mixtures of two or more metals or a metal and a non-metal and cannot be separated into their components by physical methods. But still, an alloy is considered as a mixture because it shows the properties of its constituents and can have variable composition. For example, brass is a mixture of approximately 30% zinc and 70% copper.

Components of solution-

Solute-The component of the solution that is dissolved in the solvent (usually present in lesser quantity) is called the solute.

Solvent-The component of the solution that dissolves the other component in it (usually the component present in larger amount) is called the solvent.

Example-A solution of sugar in water is a solid in liquid solution. In this solution, sugar is the solute and water is the solvent.

Solution of iodine is called tincture of iodine.

Properties of a Solution

1. Homogeneous mixture
   → A solution is a homogeneous mixture, which means it looks same everywhere.

2. Very small particles
   → The particles of solute are very tiny and cannot be seen with naked eyes. diameter 1 nm

3. Particles do not settle down
   → Solute particles do not settle at the bottom even after keeping the solution for a long time.

4. Transparent
   → A solution is transparent, so light can pass through it easily.

5. Cannot be separated by filtration
   → Solute particles are so small that they cannot be separated using filter paper.

6. Stable mixture
   → A solution is stable and does not separate on standing.

 TYPES OF SOLUTIONS-

SATURATED  SOLUTIONS	UNSATURATED SOLUTIONS
Cannot dissolve more solute at a given temperature.	Can dissolve more solute at a temperature
Contain maximum solute	Contain less solute than maximum.
Extra solutes can be settled at the bottom.	Extra solutes dissolves easily.

WHAT IS A SUSPENSION?

Non-homogeneous systems in which solids are dispersed in liquids, are called suspensions. They are heterogenous mixtures.

Properties of a Suspension 

• Suspension is a heterogeneous mixture.

 • The particles of a suspension can be seen by the naked eyes.

• The particles of a suspension scatter a beam of light passing through it and make its path visible.

 • The solute particles settle down when a suspension is left undisturbed, that is, a suspension is unstable

•      They can be separated from the mixture by the process of filtration. 

COLLOIDAL SOLUTION-

What is a Colloidal Solution?

A colloidal solution is a mixture in which very small particles of one substance are spread evenly in another substance, but do not completely dissolve.

Properties of Colloidal Solution (Easy Points)

1. Looks homogeneous but is actually heterogeneous
   → It looks same, but particles are not truly dissolved.

2. Particles are small but visible under microscope
   → We cannot see them with naked eyes.

3. Particles do not settle down
   → They stay mixed for a long time.

4. Shows Tyndall effect
   → It can scatter light (light path becomes visible).

5. Cannot be separated by filtration
   → Filter paper cannot separate the particles.

6. Stable mixture→ Does not separate on standing.

xamples of Colloidal Solution

• Milk

• Fog

• Smoke

• Butter

• Blood

• Starch solution

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Components of a Colloid

• Dispersed phase → Particles present in small amount

• Dispersion medium → Substance in which particles are mixed

📌 Example:
Milk → Fat (dispersed phase) + Water (dispersion medium).

·        How would you confirm that a colorless liquid given to you is pure water?

Ans. If the boiling and freezing points of the given liquid comes out to be  100  degree Celsius and 0 degree Celsius  respectively under one atmosphere pressure, it confirms that the given liquid is pure water.

MATTER IN OUR SURROUNDINGS

 

CHARACTERISTICS OF PARTICLES OF MATTER.

• Extremely Small Size: Particles of matter are inconceivably small, far beyond the visibility of the naked eye.
• Spaces Between Particles: There are voids or intermolecular spaces between particles, which allows substances to mix (e.g., dissolving sugar in water). This space is minimal in solids, higher in liquids, and maximum in gases.
• Constant Motion: Particles possess kinetic energy and are always in motion. In solids, they vibrate in place, while in liquids and gases, they move randomly. Increased temperature leads to faster particle movement.
• Attractive Forces: Particles of matter attract each other with varying force (intermolecular force), which dictates the state of matter—strongest in solids, weaker in liquids, and weakest in gases.
• Possess Mass: Each particle has mass, contributing to the overall mass and volume of the substance.

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.
Ans-The hot food particles have more kinetic energy  so it travel faster and more distance .Que-A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
Ans- water molecules have weak intrrmolecular force of attraction between them so they can be easily cut thats why  diver can cut the water easily.
Give reasons 
(a) A gas fills completely the vessel in which it is kept..

Ans-Gas molecules have higher intermolecular force and lower intermolecular force of attraction between them,thats why gas fill the vessel completely.

b)A gas exerts pressure on the walls of the container.

Ans-due to the continuous, rapid, and random motion of gas molecules, which frequently collide with the walls.so gas exert pressure on the wall.

🔹 Change of State of Matter

1️⃣ Melting

• Solid → Liquid

• Example: Ice → Water

• Melting point of ice = 0°C

2️⃣ Freezing

• Liquid → Solid

• Example: Water → Ice

3️⃣ Evaporation

• Liquid → Gas (below boiling point)

• Happens at all temperatures

4️⃣ Condensation

• Gas → Liquid

• Example: Water droplets on cold glass

5️⃣ Boiling

• Liquid → Gas at fixed temperature

Boiling point of water = 100°C

Factors effecting rate of evaporation-

 Factors Affecting Rate of Evaporation

1️⃣ Surface Area

• Larger surface area → faster evaporation

• Example: Clothes spread out dry faster than folded clothes.

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2️⃣ Temperature

• Higher temperature → faster evaporation

• Example: Clothes dry faster in summer.

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3️⃣ Wind Speed

• Higher wind speed → faster evaporation

• Wind carries away water vapour.

• Example: Clothes dry faster on a windy day.

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4️⃣ Humidity

• Lower humidity → faster evaporation

• If air already has more water vapour, evaporation slows.

Example: Clothes dry slowly on a humid (rainy) day.

 Melting Point (Class 9)

✅ Definition

Melting point is the temperature at which a solid changes into a liquid.

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📌 Important Example

• Melting point of ice = 0°C (273 K)

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🧠 Key Points to Remember

• At melting point, solid and liquid exist together.

• During melting, temperature remains constant.

• The heat supplied is used as latent heat of fusion.

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✍️ Why temperature remains constant at melting point?

Answer:
Because the heat supplied is used to change the state of matter, not to increase temperature.

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⭐ Importance of Melting Point

• Helps to identify a substance

• Indicates purity of a solid

• Solids with high melting point have strong force of attraction.

9️⃣ Why does a desert cooler cool better on a hot dry day?

Answer:
On a hot dry day, the air has low humidity, so evaporation of water is faster. Faster evaporation absorbs more heat from the surroundings, causing greater cooling. Hence, a desert cooler works better on a hot dry day.

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🔟 How does evaporation cause cooling?

Answer:
During evaporation, liquid particles take heat from surroundings, causing cooling.

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1️⃣1️⃣ Why should we wear cotton clothes in summer?

Answer:
Cotton absorbs sweat and allows it to evaporate easily, giving cooling effect.

1️⃣ Which of the following are matter?

Answer:
Matter: Chair, air, almonds, cold drink, smell of perfume
Not matter: Love, hate, thought, cold

Reason: Matter has mass and occupies space.

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2️⃣ Give reasons for the following:

a) Smell of hot food reaches far away
Because particles move continuously and show diffusion. At high temperature diffusion is faster.

b) A diver cuts through water
Because force of attraction between liquid particles is weak.

c) Water flows but wood does not
Water is a liquid and can flow. Wood is a solid and has fixed shape.

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3️⃣ Characteristics of particles of matter

Answer:

1. Particles are very small

2. There is space between particles

3. Particles are continuously moving

4. Particles attract each other

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4️⃣ Physical state of water

a) 25°C → Liquid
b) 0°C → Solid and liquid
c) 100°C → Liquid and gas

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5️⃣ Increasing order of force of attraction

a) Oxygen < Water < Sugar
b) Helium < Air < Oxygen

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6️⃣ Give reasons:

a) Water at room temperature is liquid

• Has fixed volume

• Has no fixed shape

• Can flow

b) Iron almirah is solid at room temperature

• Has fixed shape and volume

• Strong force of attraction

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7️⃣ Why is ice at 0°C more effective in cooling than water at 0°C?

Answer:
Ice absorbs latent heat of fusion while melting, so it removes more heat from surroundings.

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8️⃣ What is evaporation? Explain factors.

Answer:
Evaporation is the change of liquid into gas at any temperature below boiling point.

Factors affecting evaporation:

1. Surface area

2. Temperature

3. Wind speed

4. Humidity

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9️⃣ How does evaporation cause cooling?

Answer:
During evaporation, particles take heat from surroundings, causing cooling.

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🔟 Why should we wear cotton clothes in summer?

Answer:
Cotton absorbs sweat and allows fast evaporation, which cools the body.

🔥 Latent Heat of Vapourisation

✅ Definition

Latent heat of vapourisation is the amount of heat required to change a liquid into gas at its boiling point without any change in temperature.

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📌 Example

• When water at 100°C changes into steam at 100°C, it absorbs latent heat of vapourisation.

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🧠 Key Points (Very Important)

• Temperature remains constant during the change of state.

• Heat is used to overcome the force of attraction between particles.

• Gases have more energy than liquids.

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✍️ Why is latent heat of vapourisation needed?

Answer:
Because extra heat is required to completely separate liquid particles and change them into gas.

❄️ Latent Heat of Fusion

✅ Definition

Latent heat of fusion is the amount of heat required to change a solid into a liquid at its melting point without any change in temperature.

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📌 Example

• When ice at 0°C changes into water at 0°C, it absorbs latent heat of fusion.

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🧠 Key Points (Important)

• Temperature remains constant during melting.

• Heat is used to break the force of attraction between solid particles.

• Both solid and liquid exist together at melting point.

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✍️ Why is latent heat of fusion needed?

Answer:
Because extra heat is required to overcome the strong attraction between particles of a solid.

Class 9 links

sample paper link

https://drive.google.com/drive/folders/1DmwEvm7ikwyKWYoY_8i37JHhjw4olDUG?usp=drive_link

PERIODIC TEST 2 CLASS 9 PAPER SCIENCE WITH MARKING SCHEME

 

                      PM SHRI KENDRIYA VIDYALAY N.E.R. BAREILLY (2025-26)

PERIODIC TEST -2

CLASS –IX

                                                           SUBJECT – SCIENCE

TIME ALLOWED: 1:30 Hrs.                                                     MAXIMUM MARKS: 40

MCQs 

1. Which  of the following properties does not describe a compound?

a) It is composed of two or more elements

b) It is a pure substance

c)It cannot be separated into constituents by physical method

d)  it is mixed in any proportion by mass

2. During a sprinting race, Meera suddenly felt a pull where her calf muscles attached to

her leg bone. Her coach explained that a specific tissue was strained, which connects

muscles to bones and enables movement. Which type of tissue was he referring to?

(a) Ligament                (b) Tendon                      (c) Cartilage                                           (d) Bone

3.Which of the following quantities remains constant everywhere?

(a) Weight                     (b) MASS                    (c) Gravitational force       d) Acceleration due to gravity

4. Girth of stem increases due to

a) Apical meristem       b) Intercalary meristem        c) Lateral meristem            d)  vertical meristem

5.. A person standing in a moving bus that suddenly stops,the person tends to:

(a) Fall backward                   (b) Remain standing

(c) Fall sideways                   (d) Fall forward

Assertion-Reason Based Questions (1mark each)

(a) Both A and R are true and R is correct explanation of A

(b) Both A and R are true, but R is not the correct explanation of the assertion.

(c) A is true, but R is false.

Name the physical quantity(d) A is false, but R is true.

6. Assertion (A): Cardiac muscles do not get tired easily.

Reason (R): Cardiac muscles work continuously and are resistant to fatigue

7.. Assertion: When a beam of light is passed through a colloidal solution placed in a dark place the path of the beam becomes visible.

 Reason: Light gets scattered by the colloidal particles.

8.Why are the xylem and phloem called complex tissue?  and how are the different from one other

9. Shruti walking on the road.Describe her walking in terms of Newton's third law of motion  

10.Differentiate the following activities on the basis of voluntary or involuntary muscles with name

a) Jumping of the frog 

b) pumping of the heart    

c) Drawing a painting

d) Movement of chocolate in your intestine      

11.Name the physical quantity that is  product of mass of object and velocity.Write its SI unit is it vector or scalar quantity ?

12.State the factors on which the gravitational force between two objects depends.           

                           OR

A body weighs 600 N on Earth. What would be its weight on the Moon?

13.Differentiate between different types of muscular tissues with diagram and also write there functions

14. State the law of gravitation given by Newton. What is the importance of this law?

15. At Gwalior airport, Rohit has a trolley bag. He pushes the trolley on the smooth floor of the airport. Initially, the trolley is at rest. After applying a continuous force, the trolley begins to move and pick up speed.

(a) Which law of motion explains why the trolley starts moving?

(b) What is the direction of the force applied by the boy?

(c) Name the property of the trolley that resists the start of motion.

 Case study Based Questions (4 Marks)

16. A young athlete named Raj, who is a long-distance runner, experiences muscle soreness and fatigue after a grueling training session. His legs feel weak and stiff, and he's unable to continue his workout. He has also been feeling short of breath.

(a) What type of muscle tissue is primarily responsible for Raj's leg movement, enabling him to run?

(b) Describe two main characteristics of the type of muscle tissue that allows Raj to run long distances without fatigue.

(c) What other types of tissues are involved in Raj’s running, and how do they work

(d) Name sweat secreting tissue.

17.a) A solution of alcohol in water has been prepared by mixing 150 ml of alcohol with 600 ml of water. Calculate the volume. Percentage of the solution.

b) Why? Copper sulphate solution in water does not show Tyndall effect but mixture of water and milk shows .

(c) Suggest any one method by which we can increase the solubility of solution

18. A stone of 1 kg is thrown with a velocity of 20 m/s across the frozen surface of the lake and  comes to rest after travelling a distance of 50 m. What is the force of friction between the stone and ice?

MARKING SCHEME`

1.d)  it is mixed in any proportion by mass

2.    (b) Tendon  

3.     (b) mass

4.c lateral meristem.

5. (d) Fall forward

6.a

7.a

8.Xylem and phloem are called complex tissues because 
they are each composed of more than one type of cell that work together to perform a specific, unified function.

9.When Shruti walks, her feet apply an action force by pushing backward on the road, and in reaction, the road exerts an equal and opposite force (the reaction force) on her feet, pushing them forward. This forward-moving reaction force, aided by friction between her shoes and the road, is what propels Shruti and allows her to move forward.

10.

• Jumping of the frog: Voluntary 
• Pumping of the heart: Involuntary 
• Drawing a painting: Voluntary 
• Movement of chocolate in your intestine: Involuntary.

11.The physical quantity that is the product of an object's mass and velocity is called momentum. Its SI unit is the kilogram-meter per second (kg·m/s). Momentum is a vector quantity because it has both a magnitude and a direction, which is the same as the direction of the object's velocity.

12.The gravitational force between two objects depends on the product of their masses and the square of the distance between their centers. Specifically, the force is directly proportional to the product of the masses, meaning greater masses result in a stronger force, and inversely proportional to the square of the distance, meaning increasing the distance significantly reduces the force.

                                    OR

$W_{\text{Moon}}=\frac{1}{6}\cdot 600\text{N}=100\text{N}$

13.

14.

The importance of universal law of gravitation is that it explains the motion of planets around the sun, the motion of moon around the earth, and the motion of artificial satellites around the earth. It also explains the phenomena of rainfall, snowfall, and flow of water in rivers on the earth.

15

(a) The trolley starts moving because of Newton’s First Law of Motion (Law of Inertia). A body at rest remains at rest unless an external force is applied. Rohit’s push provides that external force.

(b) The direction of the force applied by the boy is in the same direction in which the trolley moves (forward, along the push).

(c) The property of the trolley that resists the start of motion is inertia of rest.

16.(a) The muscle tissue responsible for Raj’s leg movement while running is skeletal (voluntary, striated) muscle tissue.

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(b) Two main characteristics of skeletal muscle that help in long-distance running:

1. Contractile & Voluntary: They contract and relax under Raj’s conscious control, producing movement of the legs.

2. Rich in Mitochondria (especially in red muscle fibers): They provide a continuous supply of energy (ATP) through aerobic respiration, helping Raj sustain running for long periods.

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(c) Other tissues involved in running and their roles:

• Nervous tissue: Sends signals from the brain and spinal cord to muscles, coordinating movement.

• Connective tissue (bones, ligaments, tendons, cartilage): Bones act as levers, tendons attach muscles to bones, and ligaments hold joints in place.

• Epithelial tissue (lungs & blood vessels): Helps in oxygen exchange (lungs) and regulates blood flow.

• Blood (connective tissue): Transports oxygen and nutrients to muscles and removes waste like carbon dioxide and lactic acid.

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(d) The sweat-secreting tissue is epithelial tissue of sweat glands (specifically, glandular epithelium).

17.a

Given:

• Volume of alcohol (solute) = 150 ml

• Volume of water (solvent) = 600 ml

• Total volume of solution = $150 + 600 = 750}$

Now calculate:

$$\text{Volume percentage of alcohol} = \frac{150}{750} \times 100$$ $$= \frac{15000}{750} = 20$$

Final Answer: The volume percentage of alcohol in the solution is 20% (v/v).

b.Copper sulphate solution does not show Tyndall effect because it is a true solution with very small particles. Milk shows Tyndall effect because it is a colloid with larger dispersed particles that scatter light.

c.By increasing the temperature of the solvent.

• When temperature rises, solvent molecules gain more kinetic energy.

• This allows them to break solute particles apart more easily and dissolve more solute.

✅ Example: More sugar dissolves in hot water than in cold water.

18.Given data:

• Mass of stone, $m$

• Initial velocity, $u=20\text{m/s}$

• Final velocity, $v=0$

• Distance travelled, $s=50$

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Step 1: Use equation of motion

$$v^2 = u^2 + 2as$$

Substitute values:

$$0^2=(20{)}^2+2\cdot a\cdot 50$$
$$0=400+100a$$
$$a=-\frac{400}{100}=-4{\text{m/s}}^{}$$

(Negative sign shows retardation due to friction.)

Find force of friction

$$F=m\cdot a$$
$$F=1\cdot (-4)=-4\text{\hspace{0.17em}N}$$