CBSE Class 9 Science Matter in our sorroundings Sure Shot Questions Set 02

CBSE Class 9 Science Matter in our sorroundings Sure Shot Questions B. There are many more useful educational material which the students can download in pdf format and use them for studies. Study material like concept maps, important and sure shot question banks, quick to learn flash cards, flow charts, mind maps, teacher notes, important formulas, past examinations question bank, important concepts taught by teachers. Students can download these useful educational material free and use them to get better marks in examinations.  Also refer to other worksheets for the same chapter and other subjects too. Use them for better understanding of the subjects.

ASSIGNMENT QUESTIONS SET - 2
CHAPTER - 1
MATTER IN OUR SURROUNDINGS

1. What is a matter? [1 Mark]

Answer:
1. Anything that occupies space and has mass is called matter.
2. It is made up of tiny particles.

Teacher's Note:
a) Matter forms the building block of all physical objects in the universe.
b) Mass and volume are the two fundamental defining criteria for matter.

2. Sodium chloride and sugar have same appearance. Are they same or different? [1 Mark]

Answer:
1. They are different substances.
2. Sodium chloride is an ionic compound (salt) with a salty taste, whereas sugar is a carbohydrate with a sweet taste.

Teacher's Note:
a) Physical appearance alone cannot determine the chemical identity of a substance.
b) Different chemical compositions result in distinct chemical and physical properties.

3. All substances around us are alike. How? [1 Mark]

Answer:
1. All substances are alike because they all occupy space and possess mass.
2. They are all composed of matter.

Teacher's Note:
a) This question highlights the universal nature of matter.
b) Despite different appearances, the fundamental nature of having mass and volume remains identical.

4. How can we say that air is a matter? [2 Marks]

Answer:
1. Air occupies space, which can be observed when an inflated balloon expands or a football is filled with air.
2. Air has mass, which can be demonstrated by weighing an empty balloon and comparing it with the same balloon filled with air.

Teacher's Note:
a) Air is a mixture of gases that satisfies both conditions of matter.
b) Invisible substances can still be classified as matter if they possess mass and volume.

5. State the characteristics of matter? [2 Marks]

Answer:
1. Particles of matter have spaces between them.
2. Particles of matter are continuously moving and possess kinetic energy.

Teacher's Note:
a) Matter also has particles that attract each other.
b) These microscopic characteristics explain macro-level behaviors like diffusion and rigidity.

6. What are the intensive properties of matter? [2 Marks]

Answer:
1. Intensive properties are those characteristics of matter that do not depend on the amount of substance present.
2. Examples include density, boiling point, and melting point.

Teacher's Note:
a) These properties are extremely useful in identifying unknown chemical substances.
b) Splitting a sample in half does not change its intensive properties.

7. What are the extensive properties of matter? [2 Marks]

Answer:
1. Extensive properties are those characteristics of matter that depend on the amount of substance present.
2. Examples include mass, volume, and total energy.

Teacher's Note:
a) Extensive properties scale directly with the size of the system.
b) Contrast these with intensive properties which remain constant regardless of sample size.

8. State the characteristics of particles of matter. [3 Marks]

Answer:
1. Particles of matter have space between them.
2. Particles of matter are continuously moving.
3. Particles of matter attract each other.

Teacher's Note:
a) These three postulates form the foundation of the kinetic theory of matter.
b) Interparticle attraction varies across solids, liquids, and gases.

9. What is the effect of temperature on a matter? [2 Marks]

Answer:
1. An increase in temperature increases the kinetic energy of the particles, causing them to vibrate or move faster.
2. It can also overcome forces of attraction between particles, leading to a change of state.

Teacher's Note:
a) Temperature is a direct measure of average kinetic energy.
b) Heating can cause expansion or phase transitions like melting and vaporization.

10. The smell of hot sizzling food reaches us several metres away. Why? [2 Marks]

Answer:
1. Particles of hot food possess higher kinetic energy due to high temperature and diffuse rapidly through the air.
2. This allows the aroma to travel a distance of several metres quickly.

Teacher's Note:
a) This phenomenon demonstrates both diffusion and the effect of temperature on particle speed.
b) Cold food particles have lower kinetic energy and do not travel as far.

11. What is diffusion? [1 Mark]

Answer:
1. The intermixing of particles of two different types of matter on their own is called diffusion.

Teacher's Note:
a) Diffusion occurs due to the random motion of particles.
b) It is fastest in gases and slowest in solids.

12. If a bottle of perfume is opened in one corner of a room, it immediately spreads throughout the room. Why? [2 Marks]

Answer:
1. Perfume consists of volatile liquid particles that evaporate easily into gas.
2. These gas particles undergo rapid diffusion into the surrounding air currents of the room.

Teacher's Note:
a) High rate of diffusion in gases explains why odors spread quickly.
b) Molecules move from a region of higher concentration to lower concentration.

13. Name the three states of matter with examples. [2 Marks]

Answer:
1. Solid - Example: Iron or Ice.
2. Liquid - Example: Water or Milk.
3. Gas - Example: Oxygen or Air.

Teacher's Note:
a) These three states differ in rigidity, compressibility, and volume constancy.
b) Plasma and Bose-Einstein condensates are other advanced states of matter.

14. State the characteristics of solids. [3 Marks]

Answer:
1. Solids have a definite shape and a fixed volume.
2. They have negligible compressibility.
3. The forces of attraction between particles are very strong.

Teacher's Note:
a) Particles in solids are closely packed and only oscillate about their mean positions.
b) Rigidity is a hallmark property of solid matter.

15. What are the characteristics of liquids? [3 Marks]

Answer:
1. Liquids have a fixed volume but no fixed shape, taking the shape of the container.
2. They have fluid behavior and can flow easily.
3. Their compressibility is very low compared to gases.

Teacher's Note:
a) Interparticle forces in liquids are weaker than in solids but stronger than in gases.
b) Liquid particles have greater kinetic energy than solid particles.

16. What are the characteristics of gases? [3 Marks]

Answer:
1. Gases have neither a fixed shape nor a fixed volume.
2. They are highly compressible.
3. They exhibit high fluidity and fill their container completely.

Teacher's Note:
a) Interparticle spaces are maximum and forces of attraction are minimum in gases.
b) Gas particles move randomly at very high speeds.

17. What are fluids? [1 Mark]

Answer:
1. Substances that can flow easily and change their shape are called fluids, which include both liquids and gases.

Teacher's Note:
a) Fluidity is the ability to flow.
b) Both liquid and gas states share this characteristic.

18. Which of the following substances is most compressible? \(\text{CO}_2\), \(\text{H}_2\text{O}\), NaCl. [1 Mark]

Answer: (A) \(\text{CO}_2\); the official key also accepts Carbon dioxide
1. Among the given substances, carbon dioxide (\(\text{CO}_2\)) exists in the gaseous state under normal conditions.
2. Gases have large interparticle spaces, making them highly compressible compared to liquids and solids.

Teacher's Note:
a) Compressibility is directly related to the empty space between particles.
b) \(\text{H}_2\text{O}\) is a liquid and NaCl is a solid, both of which are nearly incompressible.

19. Which property of a gas results in steady pressure of the gas ? [2 Marks]

Answer:
1. Continuous random motion of gas particles and their frequent collisions with the walls of the container.
2. The average force exerted per unit area by these collisions creates a steady pressure.

Teacher's Note:
a) Gas pressure is a macroscopic manifestation of microscopic particle impacts.
b) Increasing temperature increases this collision frequency and thereby the pressure.

20. In which of the following substances, weakest inter molecular force is expected: \(\text{H}_2\text{O}\), \(\text{CH}_3\text{OH}\), [Note: Question text is truncated in PDF after \(\text{CH}_3\text{OH}\), evaluated based on standard options or context] [1 Mark]

Answer:
1. The intermolecular forces are weakest in gaseous substances compared to polar liquids like water (\(\text{H}_2\text{O}\)) and methanol (\(\text{CH}_3\text{OH}\)).
2. If the missing option is a gas, it has the weakest force; otherwise, among hydrogen-bonded liquids, comparison depends on molecular weight and polarity.

Teacher's Note:
a) Hydrogen bonding in water and methanol results in relatively strong intermolecular forces.
b) Check the complete question paper options if provided elsewhere in the set.

21. One gas mixes with another gas easily. What is this property called ? [1 Mark]

Answer:
1. Diffusion.

Teacher's Note:
a) Gases diffuse rapidly into one another because of high kinetic energy and large intermolecular spaces.
b) No external stirring is required for this mixing process.

22. Describe briefly (i) Melting point and (ii) Boiling point. [2 Marks]

Answer:
1. Melting point: The temperature at which a solid melts to become a liquid at atmospheric pressure.
2. Boiling point: The temperature at which a liquid starts boiling and changes rapidly into gas at atmospheric pressure.

Teacher's Note:
a) Both are characteristic intensive properties of pure substances.
b) Melting point indicates solid-liquid equilibrium, while boiling point indicates liquid-gas equilibrium.

23. How would you find out whether a sample of sodium chloride is pure or impure ? [2 Marks]

Answer:
1. Determine its melting point; a pure substance has a sharp and fixed melting point, whereas an impure substance melts over a range of temperatures.
2. Alternatively, check its physical and chemical properties like density or solubility, which differ for impure samples.

Teacher's Note:
a) Purity of crystalline solids is reliably tested via melting point determination.
b) Impurities lower the melting point and broaden the melting range.

24. How will you find out whether a sample of water is pure or impure ? [2 Marks]

Answer:
1. Check its boiling point; pure water boils strictly at 100°C at 1 atmospheric pressure.
2. Check if it leaves any residue upon complete evaporation, as pure water leaves no residue.

Teacher's Note:
a) Presence of dissolved salts alters both boiling and freezing points of water.
b) Electrical conductivity testing can also distinguish pure water from impure water containing ions.

25. Why do solids have a fixed shape and gases have neither a fixed shape nor a fixed volume? [3 Marks]

Answer:
1. In solids, particles are tightly packed with strong interparticle forces of attraction, restricting them to fixed positions.
2. In gases, particles have very weak intermolecular forces and large interparticle distances.
3. Gas particles possess high kinetic energy, allowing them to move freely in all directions to fill any container.

Teacher's Note:
a) State of matter is a balance between thermal energy and intermolecular forces.
b) Higher thermal energy relative to attractive forces leads to gaseous behavior.

26. What is Vaporization ? [1 Mark]

Answer:
1. The process of conversion of a liquid into its vapor or gas state is called vaporization.

Teacher's Note:
a) It can occur either through evaporation at any temperature or boiling at the boiling point.
b) Latent heat of vaporization is required for this phase change.

27. What is Sublimation ? [1 Mark]

Answer:
1. The direct conversion of a solid directly into gas without changing into a liquid state is called sublimation.

Teacher's Note:
a) Common examples include camphor, ammonium chloride, and dry ice.
b) The reverse process is called deposition.

28. What is Condensation ? [1 Mark]

Answer:
1. The process of conversion of a gas or vapor into its liquid state upon cooling is called condensation.

Teacher's Note:
a) It is the exact reverse of vaporization.
b) Heat is released during the condensation process.

29. What is Deposition ? [1 Mark]

Answer:
1. The transition of a gas directly into a solid state without passing through the liquid state is called deposition.

Teacher's Note:
a) Frost formation from water vapor is a common example of deposition.
b) It is also referred to as desublimation.

30. What is Liquefaction ? [1 Mark]

Answer:
1. The process of converting a gas into a liquid by applying high pressure and lowering the temperature is called liquefaction.

Teacher's Note:
a) Gases can be liquefied by reducing the distance between their particles.
b) High pressure and low temperature favor this phase change.

31. What is Solidification ? [1 Mark]

Answer:
1. The process of conversion of a liquid into its solid state by cooling is called solidification or freezing.

Teacher's Note:
a) This occurs at the freezing point of the liquid.
b) Kinetic energy of particles decreases during solidification.

32. What is difference between vapour and gas. [2 Marks]

Answer:
1. A gas is a substance that exists in the gaseous state at normal room temperature.
2. A vapour refers to the gaseous state of a substance that is normally a solid or liquid at room temperature.

Teacher's Note:
a) Oxygen and nitrogen are gases at room temperature.
b) Water vapour is a vapour because water exists as a liquid under normal conditions.

33. Why do the three states of matter differ ? [2 Marks]

Answer:
1. They differ due to the varying characteristics of the particles of matter.
2. Differences arise from intermolecular forces, intermolecular spaces, and the kinetic energy of particles.

Teacher's Note:
a) Solids have strong forces and negligible space between particles.
b) Gases have very weak forces and large spaces between particles.

34. Why does the temperature remain constant until whole of the solid changes into liquid, though the heat energy is constantly supplied ? [3 Marks]

Answer:
1. The supplied heat energy is used up in overcoming the forces of attraction between the particles of the solid.
2. This heat energy does not increase the kinetic energy of the particles.
3. Since kinetic energy determines temperature, the temperature remains constant during the change of state.

Teacher's Note:
a) This absorbed heat is known as the latent heat of fusion.
b) Temperature only rises after the entire solid has converted into liquid.
c) Mentioning intermolecular forces is essential to secure full credit.

35. Why does the temperature remain constant during boiling though heat is constantly supplied ? [3 Marks]

Answer:
1. The heat supplied is continuously consumed to break the forces of attraction between liquid particles.
2. It changes the state from liquid to gas without raising the average kinetic energy.
3. Therefore, the temperature stays constant at the boiling point until all liquid vaporizes.

Teacher's Note:
a) This heat energy is referred to as latent heat of vaporization.
b) Students often mistakenly write that heat stops entering the system.
c) Kinetic energy remains constant during a phase change.

36. Why does a gas fill a vessel completely ? [2 Marks]

Answer:
1. Gas particles possess very high kinetic energy and negligible intermolecular forces.
2. They move freely in all directions at high speeds, occupying the entire available volume.

Teacher's Note:
a) Gases have neither definite shape nor definite volume.
b) High kinetic energy enables complete expansion.

37. How does the state of matter changes from solid to liquid and then to gas on heating ? [3 Marks]

Answer:
1. Heating increases the kinetic energy of solid particles, making them vibrate more vigorously.
2. At the melting point, particles overcome fixed positions to form a liquid.
3. Further heating gives particles enough energy to break all bonds, converting the liquid into a gas.

Teacher's Note:
a) Energy supplied breaks intermolecular attractive forces sequentially.
b) Solid to liquid involves melting, and liquid to gas involves boiling or vaporization.
c) Kinetic energy is directly proportional to temperature.

38. Why evaporation is called surface phenomenon? [2 Marks]

Answer:
1. Evaporation takes place only at the exposed surface of the liquid.
2. Molecules at the surface have higher kinetic energy than interior particles and escape into the atmosphere.

Teacher's Note:
a) Unlike boiling, which occurs throughout the bulk of the liquid, evaporation is restricted to the surface.
b) Surface particles easily break away from intermolecular bonds.

39. List two processes from which it may be concluded that the particles of a gas move continuously. [2 Marks]

Answer:
1. Diffusion, where gases from two different substances mix spontaneously.
2. Effusion or the spreading of a smell of perfume or incense stick across a room.

Teacher's Note:
a) Random motion of particles causes rapid mixing.
b) Both phenomena provide direct evidence of continuous particle movement.

40. At what temperature does solid ice and liquid water co-exist together? [1 Mark]

Answer:
1. Solid ice and liquid water co-exist together at 0°C (or 273K).

Teacher's Note:
a) This is the normal melting point of ice and freezing point of water.

41. What is common among the three states of matter? [2 Marks]

Answer:
1. All three states are composed of tiny particles (atoms or molecules).
2. The particles in all three states possess kinetic energy and exert forces of attraction on one another.

Teacher's Note:
a) Fundamental particle nature is identical across all states.
b) Differences arise from particle spacing and motion intensity.

42. Which property of gas is used in supplying oxygen cylinders to hospitals? [1 Mark]

Answer:
1. High compressibility and liquefaction under high pressure.

Teacher's Note:
a) Large volumes of gas can be compressed into small metal cylinders.

43. A substance x was highly compressible and could easily be liquefied. it could also take the shape of the container. Predict the nature of the substance [2 Marks]

Answer:
1. The substance x is in the gaseous state.
2. Gases are highly compressible, can be easily liquefied under pressure, and take the shape of any container.

Teacher's Note:
a) High compressibility is a hallmark property of gases.
b) Ability to fill containers completely confirms the gaseous state.

44. What is the state of water at 100 degree celsius, zero degree celsius and 4 degree celsius? [3 Marks]

Answer:
1. At 100°C, water exists as a liquid and gas (steam) co-existing together.
2. At 0°C, water exists as a solid (ice) and liquid co-existing together.
3. At 4°C, water exists purely in the liquid state.

Teacher's Note:
a) Phase change boundaries allow solid-liquid or liquid-gas co-existence.
b) Water has maximum density at 4°C where it is strictly liquid.
c) Mentioning both co-existing states at 0°C and 100°C is important.

45. Can a liquid turn into vapor without heating? [1 Mark]

Answer:
1. Yes, a liquid can turn into vapour without heating through the process of evaporation at any temperature below its boiling point.

Teacher's Note:
a) Evaporation occurs naturally at all temperatures using surrounding thermal energy.

46. What do you mean by Latent heat of Fusion? [2 Marks]

Answer:
1. Latent heat of fusion is the amount of heat energy required to change 1 kg of a solid into liquid at atmospheric pressure at its melting point.
2. It does not raise the temperature during the phase change.

Teacher's Note:
a) The word latent means hidden.
b) Energy is utilized to break intermolecular bonds.

47. What is compressibility? How it is negligible in solids? [2 Marks]

Answer:
1. Compressibility is the property due to which a substance reduces its volume under high applied pressure.
2. It is negligible in solids because particles are tightly packed with minimum intermolecular space.

Teacher's Note:
a) Solids are rigid and incompressible due to strong interparticle forces.
b) Negligible space leaves no room for particles to move closer.

48. Two cubes of ice are pressed hard between two palms. After releasing the pressure, the cubes join together. Why? [2 Marks]

Answer:
1. Increasing pressure lowers the melting point of ice, causing the surface layer to melt into water.
2. When pressure is released, the melting point normalizes, and the water refreezes, joining the two cubes.

Teacher's Note:
a) Regelation is the scientific term for this phenomenon.
b) Pressure melting and subsequent refreezing bond the ice pieces.

49. Explain why ice has lower density than water? [2 Marks]

Answer:
1. Ice has a cage-like open crystal structure formed by hydrogen bonding.
2. This structure leaves large empty spaces between molecules, making its volume larger and density lower than liquid water.

Teacher's Note:
a) Density equals mass divided by volume.
b) Due to expansion upon freezing, ice floats on water.

50. Give one similarity between a liquid and a gas and one dissimilarity. [2 Marks]

Answer:
1. Similarity: Both fluids lack a fixed shape and take the shape of the container.
2. Dissimilarity: Liquids have a fixed volume and are largely incompressible, whereas gases have neither a fixed volume nor fixed shape and are highly compressible.

Teacher's Note:
a) Fluids share the ability to flow.
b) Compressibility and volume boundaries differentiate them.

51. What property of gas is utilized when natural gas is supplied for vehicles. [1 Mark]

Answer:
1. High compressibility.

Teacher's Note:
a) Compressed Natural Gas (CNG) stores large amounts of gas in small vehicle tanks.

52. What are ‘intermolecular forces’? How are these related to the three states of matter ? [3 Marks]

Answer:
1. Intermolecular forces are the forces of attraction or repulsion between neighboring particles.
2. In solids, these forces are very strong, holding particles in fixed positions.
3. In liquids, forces are moderate allowing flow, while in gases they are extremely weak, enabling free particle movement.

Teacher's Note:
a) Force strength dictates physical state rigidity and structure.
b) Thermal energy opposes intermolecular forces.
c) All three states depend directly on this balance.

53. Separate the following substances in groups of high and low intermolecular force: Ice, sulphur vapour, nitrogen, sugar, copper, air, salt, plastic. [2 Marks]

Answer:
1. High Intermolecular Force (Solids): Ice, sugar, copper, salt, plastic.
2. Low Intermolecular Force (Gases/Vapours): Sulphur vapour, nitrogen, air.

Teacher's Note:
a) Solids possess high intermolecular forces.
b) Gases and vapours possess low intermolecular forces.

54. Which of the following substances you expect strongest and in which weakest intermolecular force: Water, alcohol, sugar, sodium chloride, carbon dioxide. [2 Marks]

Answer:
1. Strongest intermolecular force: Sodium chloride (or sugar, being solid ionic/molecular crystal lattices).
2. Weakest intermolecular force: Carbon dioxide (being a gas at room temperature).

Teacher's Note:
a) Ionic solids like sodium chloride have very strong interparticle forces.
b) Gases like carbon dioxide have the weakest forces.

55. Why are gases compressible but liquids not ? [2 Marks]

Answer:
1. Gas particles have large empty spaces between them, which can be reduced under pressure.
2. Liquid particles are closely packed with negligible empty space between them, making further compression impossible.

Teacher's Note:
a) Compressibility depends directly on interparticle space.
b) Liquids and solids are nearly incompressible.

56. Compare the process of boiling and vaporization. [3 Marks]

Answer:
1. Boiling occurs at a fixed temperature called the boiling point, whereas vaporization can occur at any temperature.
2. Boiling is a bulk phenomenon taking place throughout the liquid, while vaporization (evaporation) is a surface phenomenon.
3. Boiling is a rapid process, whereas vaporization is a slow, continuous process.

Teacher's Note:
a) Evaporation is a type of vaporization occurring below the boiling point.
b) Both involve conversion of liquid to gas.
c) Distinguishing bulk versus surface behavior is crucial.

57. How is pressure developed in a container full of a gas ? [2 Marks]

Answer:
1. Gas particles are in continuous random motion at high speeds.
2. They collide with one another and continuously strike the walls of the container, exerting force per unit area, which is pressure.

Teacher's Note:
a) Kinetic theory of gases explains pressure through collisions.
b) Higher temperature increases collision frequency and pressure.

58. What are the applications of interconversion of states of matter ? [3 Marks]

Answer:
1. Liquefaction of gases allows storing petroleum gas as LPG and oxygen in hospital cylinders.
2. Refrigeration and air conditioning use phase changes of coolants to absorb and release heat.
3. Water cycle relies on continuous evaporation and condensation to maintain planetary water balance.

Teacher's Note:
a) Interconversion principles are widely applied in industry and daily life.
b) Phase changes regulate temperature and energy transfer.
c) Providing diverse industrial and natural examples secures full marks.

59. What happens to a gas if its inter molecular space is reduced ? [2 Marks]

Answer:
1. Reducing intermolecular space increases pressure and intermolecular forces.
2. If space is reduced sufficiently by cooling and compression, the gas liquefies into a liquid state.

Teacher's Note:
a) Compression forces gas molecules closer together.
b) Transition from gas to liquid occurs when spacing matches liquid density.

60. Explain how lumps of ice are more effective cooling than water at 273K. [3 Marks]

Answer:
1. Ice at 273K needs to absorb latent heat of fusion to convert into water at 273K.
2. Therefore, 1 kg of ice at 273K extracts much more heat energy from the surroundings than 1 kg of water at 273K.
3. This extra heat absorption capacity makes ice far more effective for cooling.

Teacher's Note:
a) Latent heat of fusion provides additional cooling power.
b) Water at 273K cannot absorb this extra latent heat.
c) Mentioning phase change heat absorption is essential.

Please click the link below to download CBSE Class 9 Science Matter in our sorroundings Sure Shot Questions B.