Class 9 Chapter 1 "Matter in Our Surroundings" Sample Paper

Class 9 Chapter 1 “Matter in Our Surroundings” Sample Paper

CLASS IX – SCIENCE Chapter 1: Matter in Our Surroundings

Time Allowed: 3 Hours Maximum Marks: 80

General Instructions:

This question paper consists of 5 sections: A, B, C, D, and E.
All questions are compulsory. However, an internal choice of approximately 33% has been provided in Sections B, C, and D. You have to attempt only one of the alternatives in such questions.
The question paper includes 50% competency-based questions.
Section A has 20 questions carrying 1 mark each.
- 16 Simple/Complex MCQs.
- 04 Assertion-Reasoning Type Questions.
Section B has 6 Short Answer (SA) type questions carrying 2 marks each.
Section C has 7 Short Answer (SA) type questions carrying 3 marks each.
Section D has 3 Long Answer (LA) type questions carrying 5 marks each.
Section E has 3 source-based/case-based/passage-based/integrated units of assessment (04 marks each) with sub-parts of values 1, 2, or 3 marks.

Section A (20 Marks) (16 MCQs and 4 Assertion-Reasoning Type Questions)

Multiple Choice Questions (1 x 16 = 16 Marks)

According to modern-day scientists, matter can be classified based on its physical properties and: (a) Biological characteristics (b) Chemical nature (c) Electrical conductivity (d) Magnetic properties
Which of the following statements about particles of matter is incorrect? (a) Particles of matter have space between them. (b) Particles of matter are continuously moving. (c) Particles of matter attract each other. (d) Particles of matter are visible to the naked eye.
The SI unit of mass is: (a) Gram (b) Pound (c) Kilogram (d) Milligram
Which of the following is not considered “matter” as per the definition provided? (a) Air (b) Almonds (c) Love (d) Water
The process by which a solid changes directly into a gaseous state without passing through the liquid state is called: (a) Melting (b) Evaporation (c) Sublimation (d) Condensation
When the temperature of solids increases, the kinetic energy of their particles: (a) Decreases (b) Remains the same (c) Increases (d) First decreases then increases
Boiling is described as a: (a) Surface phenomenon (b) Bulk phenomenon (c) Molecular phenomenon (d) Diffusion phenomenon
The melting point of ice in Kelvin is approximately: (a) 0 K (b) 100 K (c) 273 K (d) 373 K
Particles in water at 0°C (273 K) have more energy compared to particles in ice at the same temperature. This extra energy is due to: (a) Kinetic energy (b) Potential energy (c) Latent heat of fusion (d) Latent heat of vaporisation
Which state of matter has the maximum space between its constituent particles? (a) Solid (b) Liquid (c) Gas (d) Plasma
Which of the following factors would decrease the rate of evaporation? (a) Increase in surface area (b) Increase in temperature (c) Decrease in humidity (d) Increase in humidity
Solid carbon dioxide is commonly known as: (a) Heavy water (b) Dry ice (c) Soft ice (d) Solid gas
A rubber band is considered a solid because: (a) It changes shape under force and does not regain it. (b) It breaks if excessive force is applied, and regains shape when force is removed. (c) It can be compressed easily. (d) It has minute holes where air is trapped.
The intermixing of particles of two different types of matter on their own is called: (a) Condensation (b) Evaporation (c) Diffusion (d) Sublimation
What is the common unit of measuring volume? (a) cubic metre (m³) (b) kilogram (kg) (c) litre (L) (d) pascal (Pa)
The pressure exerted by a gas is due to: (a) The weight of the gas (b) The force exerted by gas particles per unit area on the walls of the container (c) The attraction between gas particles (d) The volume of the container

Assertion-Reasoning Type Questions (1 x 4 = 4 Marks) (In the following questions, a statement of Assertion (A) is followed by a statement of Reason (R). Choose the correct option.) (a) Both A and R are true and R is the correct explanation of A. (b) Both A and R are true but R is not the correct explanation of A. (c) A is true but R is false. (d) A is false but R is true.

Assertion (A): The smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go close. Reason (R): With an increase in temperature, the kinetic energy of particles increases, causing them to move faster.
Assertion (A): Ice floats on water. Reason (R): Liquids generally have lower density as compared to solids.
Assertion (A): Gases are highly compressible. Reason (R): Gases have a large amount of space between their particles.
Assertion (A): Evaporation causes cooling. Reason (R): Particles at the surface absorb energy from the surroundings to regain the energy lost during evaporation.

Section B (12 Marks) (Short Answer Type Questions – 2 marks each)

Define matter and provide two examples.
Convert the temperature 300 K to the Celsius scale.
State any two characteristics of the particles of matter.
(a) Why is a diver able to cut through water in a swimming pool? (b) Which property of matter does this observation show? OR Explain the term ‘diffusion’. Give one example.
What is the ‘latent heat of fusion’?
Give two reasons to justify why water at room temperature (25°C) is a liquid. OR Give two reasons to justify why an iron almirah at room temperature is a solid.

Section C (21 Marks) (Short Answer Type Questions – 3 marks each)

Describe Activity 1.1 from the chapter and explain how it demonstrates that matter is made up of particles and that there is space between them.
Explain why the smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go close. Relate your explanation to the kinetic energy of particles.
(a) Differentiate between boiling and evaporation based on whether they are a surface or bulk phenomenon. (b) Give one more point of difference between them. OR Explain how the kinetic energy of particles changes with an increase in temperature, and what impact this has on the state of matter.
List any three factors that affect the rate of evaporation.
Explain why we see water droplets on the outer surface of a glass containing ice-cold water.
(a) Define melting point. (b) Define boiling point. OR (a) Define sublimation. (b) Define deposition.
Convert the following temperatures to the Kelvin scale: (a) 25°C (b) 373°C OR State and explain any three characteristics of the particles of matter.

Section D (15 Marks) (Long Answer Type Questions – 5 marks each)

Describe the three states of matter (solid, liquid, and gas) based on their physical properties. Include discussions on their shape, volume, compressibility, fluidity/rigidity, and the force of attraction between particles.
Explain the phenomenon of latent heat during a change of state. Why does the temperature of a substance remain constant during its melting point, even when heat is continuously supplied? Define latent heat of fusion. OR Particles in steam at 373 K (100°C) have more energy than water at the same temperature. Explain this observation. Define latent heat of vaporisation.
Discuss how changes in temperature and pressure can bring about a change in the state of matter. Provide examples for solid to liquid, liquid to gas due to temperature, and liquefaction of gases due to pressure. OR Describe three activities from the chapter that illustrate the characteristics of particles of matter (e.g., space between them, continuous movement, attraction). For each activity, clearly state the characteristic it demonstrates.

Section E (12 Marks) (Source-based/Case-based/Passage-based/Integrated Units of Assessment – 4 marks each)

37. Read the following passage and answer the questions that follow: In an open vessel, the liquid keeps on evaporating. The particles of liquid absorb energy from the surrounding to regain the energy lost during evaporation. This absorption of energy from the surroundings makes the surroundings cold. During summer, we perspire more because of the mechanism of our body which keeps us cool. We know that during evaporation, the particles at the surface of the liquid gain energy from the surroundings or body surface and change into vapour. The heat energy equal to the latent heat of vaporisation is absorbed from the body leaving the body cool. Cotton, being a good absorber of water helps in absorbing the sweat and exposing it to the atmosphere for easy evaporation.

(1 Mark) (a) How does evaporation contribute to cooling?

(2 Marks) (b) Explain why wearing cotton clothes is recommended in summer.

(1 Mark) (c) Give one other example from daily life where cooling due to evaporation is observed (apart from sweating).

38. Read the following passage and answer the questions that follow: We observe that liquids have no fixed shape but have a fixed volume. They take up the shape of the container in which they are kept. Liquids flow and change shape, so they are not rigid but can be called fluid. We have seen that solids and liquids can diffuse into liquids. The gases from the atmosphere diffuse and dissolve in water. These gases, especially oxygen and carbon dioxide, are essential for the survival of aquatic animals and plants. The rate of diffusion of liquids is higher than that of solids. This is due to the fact that in the liquid state, particles move freely and have greater space between each other as compared to particles in the solid state.

(1 Mark) (a) What property of liquids allows them to be called ‘fluid’?

(2 Marks) (b) How do aquatic animals manage to breathe under water?

(1 Mark) (c) Compare the rate of diffusion in liquids and solids based on the information provided.

39. Read the following passage and answer the questions that follow: A change of state directly from solid to gas without changing into liquid state is called sublimation and the direct change of gas to solid without changing into liquid is called deposition. Have you heard of solid carbon dioxide (CO2)? It is stored under high pressure. Solid CO2 gets converted directly into gaseous state on decrease of pressure to 1 atmosphere without coming into liquid state. This is the reason that solid carbon dioxide is also known as dry ice. Thus, we can say that pressure and temperature determine the state of a substance, whether it will be solid, liquid or gas.

(1 Mark) (a) What is deposition?

(2 Marks) (b) What is ‘dry ice’ and why is it called so?

(1 Mark) (c) Besides temperature, what other factor significantly determines the state of a substance?

Here are the answers to the question paper, drawing on the information provided in the NCERT Class 9 Science Chapter 1 “Matter in Our Surroundings” excerpts.

CLASS IX – SCIENCE
Chapter 1: Matter in Our Surroundings
Answer Key

Section A (20 Marks)
(16 MCQs and 4 Assertion-Reasoning Type Questions)

Multiple Choice Questions (1 x 16 = 16 Marks)

(b) Chemical nature
(d) Particles of matter are visible to the naked eye.
(c) Kilogram
(c) Love
(c) Sublimation
(c) Increases
(b) Bulk phenomenon
(c) 273 K
(c) Latent heat of fusion
(c) Gas
(d) Increase in humidity
(b) Dry ice
(b) It breaks if excessive force is applied, and regains shape when force is removed.
(c) Diffusion
(c) Litre (L)
(b) The force exerted by gas particles per unit area on the walls of the container

Assertion-Reasoning Type Questions (1 x 4 = 4 Marks)

(a) Both A and R are true and R is the correct explanation of A.
(c) A is true but R is false.
(a) Both A and R are true and R is the correct explanation of A.
(a) Both A and R are true and R is the correct explanation of A.

Section B (12 Marks)
(Short Answer Type Questions – 2 marks each)

Matter is everything in the universe that occupies space and has mass.
Examples: Air, water, stones, plants, animals.
To convert Kelvin to Celsius, subtract 273 from the Kelvin temperature.
300 K = 300 – 273 = 27°C.
Any two of the following:
- Particles of matter have space between them.
- Particles of matter are continuously moving.
- Particles of matter attract each other.
(a) A diver is able to cut through water in a swimming pool because the particles of water have forces of attraction between them that are not strong enough to completely hold them in a rigid structure, allowing them to be overcome.
(b) This observation shows that particles of matter have space between them and that the strength of the force of attraction varies between different types of matter (it is weaker in liquids than in solids).
OR
Diffusion is the intermixing of particles of two different types of matter on their own.
Example: The spreading of the smell of a lit incense stick in a room, or the spreading of ink in water.
The latent heat of fusion is defined as the amount of heat energy that is required to change 1 kg of a solid into liquid at atmospheric pressure at its melting point.
Water at room temperature (25°C) is a liquid because:
- It has no fixed shape but a fixed volume, taking up the shape of the container.
- It flows easily and is not rigid, indicating liquid properties.
- Its melting point is 0°C and boiling point is 100°C, so at 25°C, it is in its liquid state.
  OR
  An iron almirah at room temperature is a solid because:
- It has a definite shape and distinct boundaries.
- It possesses a fixed volume.
- It is rigid and has negligible compressibility.

Section C (21 Marks)
(Short Answer Type Questions – 3 marks each)

Activity 1.1 Description:
A 100 mL beaker is filled halfway with water, and the water level is marked. Some salt (or sugar) is dissolved in the water with a glass rod. It is then observed whether the water level changes.
Demonstration:
It is observed that the water level does not change. This is explained by the idea that matter is made up of particles. The particles of salt (or sugar) get into the spaces between the particles of water, thereby showing that matter is made up of particles and that there is enough space between particles of matter.
The smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go close, due to the difference in the kinetic energy of the particles.
- Particles of matter are continuously moving and possess kinetic energy.
- As the temperature rises, the kinetic energy of the particles increases, causing them to move faster.
- Hot sizzling food has a higher temperature, so its aroma particles move at a higher speed and diffuse much faster and more effectively into the air particles, allowing the smell to travel several metres away. In contrast, cold food particles have lower kinetic energy, move slower, and diffuse less rapidly, meaning one has to go closer to detect the smell.
(a) Differentiation between Boiling and Evaporation:
- Boiling is a bulk phenomenon. Particles from the bulk (whole) of the liquid gain enough energy to change into the vapour state.
- Evaporation is a surface phenomenon. Particles from the surface of the liquid gain enough energy to overcome the forces of attraction and change into the vapour state.
  (b) One more point of difference:
- Boiling occurs only at a specific temperature, known as the boiling point.
- Evaporation can take place at any temperature below the boiling point.
- (Alternatively: Boiling is a rapid process with visible bubbling, while evaporation is a slower process).
  OR
  Kinetic Energy and Temperature:
  Particles of matter are continuously moving and possess kinetic energy. When the temperature of a substance increases, the kinetic energy of its particles also increases. This means the particles start moving or vibrating with greater speed.
  Impact on State of Matter:
- Solids to Liquids: In solids, increased kinetic energy causes particles to vibrate with greater speed. The energy supplied by heat overcomes the forces of attraction, allowing particles to leave their fixed positions and move more freely, leading to the solid melting into a liquid.
- Liquids to Gases: In liquids, as more heat energy is supplied, particles move even faster. At a certain temperature (boiling point), they gain enough energy to completely break free from the forces of attraction and change into a gaseous state.
The rate of evaporation is affected by the following factors:
- Surface Area: An increase in surface area increases the rate of evaporation (e.g., spreading clothes for drying).
- Temperature: An increase in temperature increases the rate of evaporation, as more particles gain kinetic energy to enter the vapour state.
- Humidity: A decrease in humidity (amount of water vapour in air) increases the rate of evaporation, as the air can hold more water vapour.
- Wind Speed: An increase in wind speed increases the rate of evaporation, as water vapour particles move away with the wind, reducing water vapour in the surroundings.
  (Any three of the above).
We see water droplets on the outer surface of a glass containing ice-cold water due to condensation.
- The water vapour present in the air (from the atmosphere) comes in contact with the cold outer surface of the glass tumbler.
- The cold surface causes the water vapour to lose energy.
- Upon losing energy, the water vapour gets converted into the liquid state, which condenses and appears as tiny water droplets on the outer surface of the tumbler.
(a) Melting point: The minimum temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point.
(b) Boiling point: The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point.
OR
(a) Sublimation: A change of state directly from solid to gas without changing into liquid state is called sublimation.
(b) Deposition: The direct change of gas to solid without changing into liquid state is called deposition.
To convert a temperature on the Celsius scale to the Kelvin scale, you have to add 273 to the given temperature.
(a) 25°C: 25 + 273 = 298 K
(b) 373°C: 373 + 273 = 646 K
OR
Three characteristics of the particles of matter:
- Particles of matter have space between them: This is demonstrated by activities like dissolving salt or sugar in water, where the particles of salt/sugar get into the spaces between water particles without a noticeable change in volume.
- Particles of matter are continuously moving: This property is evident from the diffusion of various substances, such as the spreading smell of an incense stick or the intermixing of ink in water. This continuous movement is due to their kinetic energy, which increases with temperature.
- Particles of matter attract each other: There are forces of attraction between particles that keep them together. The strength of this force varies for different types of matter, as seen when trying to break an iron nail, a piece of chalk, or cutting the surface of water.

Section D (15 Marks)
(Long Answer Type Questions – 5 marks each)

The three states of matter—solid, liquid, and gas—differ significantly in their physical properties due to variations in the arrangement and forces of attraction between their constituent particles.
- 1. The Solid State:
  - Shape: Solids have a definite shape.
  - Volume: They have a fixed volume.
  - Compressibility: Solids have negligible compressibility.
  - Fluidity/Rigidity: They are rigid and have a tendency to maintain their shape, even when subjected to outside force. They may break under excessive force but resist changing shape.
  - Force of Attraction: The forces of attraction between particles in solids are maximum, holding the particles very close together in fixed positions. Particles mostly vibrate about their mean positions.
  - Examples: A pen, a book, an iron nail, sugar crystals.
- 2. The Liquid State:
  - Shape: Liquids have no fixed shape and take up the shape of the container in which they are kept.
  - Volume: They have a fixed volume.
  - Compressibility: Liquids have low compressibility (more than solids, less than gases).
  - Fluidity/Rigidity: They are fluid and flow easily, hence they are not rigid.
  - Force of Attraction: The forces of attraction between particles in liquids are intermediate, weaker than in solids but stronger than in gases. This allows particles to move freely and slip and slide over each other.
  - Diffusion: Solids, liquids, and gases can diffuse into liquids, with the rate of diffusion in liquids being higher than in solids.
  - Examples: Water, cooking oil, milk, juice.
- 3. The Gaseous State:
  - Shape: Gases have no definite shape and take the shape of the container.
  - Volume: They have no fixed volume and will completely fill the vessel in which they are kept.
  - Compressibility: Gases are highly compressible compared to solids and liquids. This property is used in LPG, CNG, and oxygen cylinders.
  - Fluidity/Rigidity: Gases are highly fluid, and their particles move about randomly at high speed. There is no order in the arrangement of particles.
  - Force of Attraction: The forces of attraction between particles in gases are minimum, and there is a large amount of space between them.
  - Pressure: Due to random movement, gas particles hit each other and the walls of the container, exerting pressure.
  - Diffusion: Gases diffuse very fast into other gases due to high particle speed and large spaces between them.
The phenomenon of latent heat occurs during a change of state. When a substance undergoes a change from one state to another (e.g., solid to liquid or liquid to gas), heat energy is continuously supplied, but the temperature of the substance remains constant at the melting or boiling point.
- Explanation for Constant Temperature during Melting:
  When heat is continuously supplied to a solid at its melting point (e.g., ice at 0°C), this heat energy is not used to increase the kinetic energy of the particles, and thus, it does not raise the temperature of the substance. Instead, this heat energy gets used up in changing the state by overcoming the strong forces of attraction between the particles of the solid. This allows the particles to break free from their fixed positions and start moving more freely, converting the solid into a liquid. Because this heat energy is absorbed without showing a rise in temperature, it is considered to be ‘hidden’ and is known as latent heat. Only after all the solid has converted into a liquid will the temperature begin to rise again as more heat is supplied to the liquid.
- Latent Heat of Fusion:
  The amount of heat energy that is required to change 1 kg of a solid into liquid at atmospheric pressure at its melting point is known as the latent heat of fusion. This is why particles in water at 0°C (273 K) have more energy than particles in ice at the same temperature, as they have absorbed this latent heat.
  OR
- Explanation: Steam vs. Water at 373 K (100°C):
  Particles in steam, that is, water vapour at 373 K (100°C), have more energy than water at the same temperature (373 K or 100°C). This is because when water boils and changes into steam, the particles of water absorb extra energy in the form of latent heat of vaporisation from the heat source. This absorbed latent heat provides the necessary energy for the liquid particles to overcome the forces of attraction between them and break free to become gaseous particles, without increasing the temperature of the substance beyond its boiling point. Therefore, steam carries this additional hidden energy, making it capable of causing more severe burns than boiling water at the same temperature.
- Latent Heat of Vaporisation:
  The latent heat of vaporisation is the heat energy required to change 1 kg of a liquid to gas at atmospheric pressure at its boiling point.
The state of matter can be changed into another state by altering temperature or pressure.
- Effect of Change of Temperature:
  - Solid to Liquid (Melting): When a solid (like ice) is heated, the supplied energy increases the kinetic energy of its particles. They start vibrating with greater speed. At the melting point (e.g., 0°C for ice), the heat energy supplied (latent heat of fusion) overcomes the forces of attraction between particles. The particles leave their fixed positions and start moving more freely, converting the solid into a liquid (water).
  - Liquid to Gas (Boiling/Vaporisation): If more heat energy is supplied to a liquid (like water), its particles move even faster. At a specific temperature, the boiling point (e.g., 100°C for water), particles gain enough energy (latent heat of vaporisation) to completely break free from the forces of attraction of other particles and change into the gaseous state (water vapour or steam).
- Effect of Change of Pressure:
  - Liquefaction of Gases (Gas to Liquid): Gases can be liquefied by applying pressure and reducing temperature. When pressure is applied, the particles of a gas are forced closer together. If the temperature is also lowered, the kinetic energy of the particles reduces, making it easier for the intermolecular forces of attraction to hold them together, thereby converting the gas into a liquid.
  - Example: Solid Carbon Dioxide (Dry Ice): Solid CO2 is stored under high pressure. When the pressure is decreased to 1 atmosphere, it converts directly into the gaseous state without passing through the liquid state. This is why it is called dry ice. Compressed gases like LPG (Liquefied Petroleum Gas) used for cooking and CNG (Compressed Natural Gas) used as fuel in vehicles are practical examples of gases liquefied by high pressure.
    Thus, pressure and temperature jointly determine the state of a substance.
    OR
    Here are three activities from the chapter that illustrate characteristics of particles of matter:
- 1. Activity 1.1 (Dissolving salt/sugar in water):
  - Characteristic Demonstrated: Particles of matter have space between them.
  - Explanation: In this activity, salt (or sugar) is dissolved in water. Despite adding a substance, the level of water in the beaker does not change significantly. This observation suggests that the particles of salt get into the spaces between the particles of water, indicating that there are vacant spaces between the constituent particles of matter.
- 2. Activity 1.3 (Spreading of smell from an incense stick):
  - Characteristic Demonstrated: Particles of matter are continuously moving.
  - Explanation: When an unlit incense stick is placed in a corner, its smell is only noticeable when one goes very close. However, once lit, the smell rapidly spreads across a distance. This is because the particles of the aroma from the hot incense stick move quickly due to higher kinetic energy and intermix (diffuse) with the moving particles of air, reaching a person sitting far away.
- 3. Activity 1.7 (Breaking an iron nail, a piece of chalk, and a rubber band) / Activity 1.8 (Cutting the surface of water with fingers):
  - Characteristic Demonstrated: Particles of matter attract each other, and the strength of this force varies.
  - Explanation: In Activity 1.7, it is observed that it is very difficult to break an iron nail, easier to break a piece of chalk, and a rubber band changes shape under force but regains it (unless excessive force is applied). This shows that particles of matter are held together by forces of attraction, but the strength of these forces varies considerably from one substance to another (strongest in iron, weakest in chalk, intermediate in a rubber band). Similarly, in Activity 1.8, we are not able to easily cut the surface of water with our fingers, suggesting that there is a force of attraction holding the water particles together.

Section E (12 Marks)
(Source-based/Case-based/Passage-based/Integrated Units of Assessment – 4 marks each)

37. Read the following passage and answer the questions that follow:
(a) (1 Mark) How does evaporation contribute to cooling?
Evaporation contributes to cooling because the particles of the liquid absorb energy from the surroundings to regain the energy lost during evaporation. This absorption of energy from the surroundings makes the surroundings cold.

(b) (2 Marks) Explain why wearing cotton clothes is recommended in summer.
During summer, our body perspires more as a mechanism to keep us cool. Evaporation of sweat from the skin causes cooling. Cotton is a good absorber of water, so it effectively absorbs the sweat from our body. By absorbing sweat and exposing it to the atmosphere, cotton facilitates easy and rapid evaporation. The heat energy equivalent to the latent heat of vaporisation is absorbed from the body during this process, leaving the body cool.

(c) (1 Mark) Give one other example from daily life where cooling due to evaporation is observed (apart from sweating).
* People sprinkle water on the roof or open ground after a hot sunny day, as the large latent heat of vaporisation of water helps cool the hot surface.
* Our palm feels cold when we put some acetone, petrol, or perfume on it because these liquids evaporate quickly and absorb energy from our palm.
* Water kept in an earthen pot (matka) becomes cool during summer due to evaporation from its porous surface.
* A desert cooler cools better on a hot dry day due to increased evaporation.
(Any one of the above).

38. Read the following passage and answer the questions that follow:
(a) (1 Mark) What property of liquids allows them to be called ‘fluid’?
Liquids flow and change shape, which is why they are called fluid.

(b) (2 Marks) How do aquatic animals manage to breathe under water?
Aquatic animals manage to breathe under water because gases from the atmosphere, especially oxygen, diffuse and dissolve in water. They utilize this dissolved oxygen for survival.

(c) (1 Mark) Compare the rate of diffusion in liquids and solids based on the information provided.
The rate of diffusion of liquids is higher than that of solids. This is because particles in the liquid state move freely and have greater space between each other compared to particles in the solid state.

39. Read the following passage and answer the questions that follow:
(a) (1 Mark) What is deposition?
Deposition is the direct change of gas to solid without changing into the liquid state.

(b) (2 Marks) What is ‘dry ice’ and why is it called so?
Solid carbon dioxide (CO2) is commonly known as dry ice. It is called dry ice because it gets converted directly into the gaseous state upon a decrease of pressure to 1 atmosphere, without ever passing through the liquid state. This process is known as sublimation.

(c) (1 Mark) Besides temperature, what other factor significantly determines the state of a substance?
Besides temperature, pressure significantly determines the state of a substance, whether it will be solid, liquid, or gas.