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Class 9 Matter in Our Surroundings Question Answer

Last updated on August 30th, 2023 at 01:45 am

Q: How does the kinetic energy of particles change with an increase in temperature?
A: As the temperature increases, the kinetic energy of particles also increases, and they move faster.

 

Q: What is diffusion?
A: Diffusion is the intermixing of particles of two different types of matter on their own by getting into the spaces between the particles.

 

Answer the following Questions in 4-5 Lines.

 Q: What are the two types of classification of matter based on physical properties and chemical nature?
A: The two types of classification of matter based on physical properties and chemical nature are:
Physical classification: based on physical properties like color, texture, and shape.
Chemical classification: based on chemical properties like composition, reactivity, and bonding.

 

Q: How do the characteristics of particles of matter vary in different states of matter?
A: The characteristics of particles of matter vary in different states of matter. In solids, particles are tightly packed, have a definite shape, distinct boundaries, and fixed volumes. In liquids, particles are less tightly packed, have no fixed shape, but have a fixed volume. In gases, particles are far apart, have no fixed shape, and no fixed volume.

 

Q: What is the difference between solids and liquids?
A: Solids have a definite shape, and fixed volumes, while liquids have no fixed shape but have a fixed volume. Solids are rigid, while liquids are not rigid and can be called fluid.

 

Q: Why are gases, especially oxygen and carbon dioxide, essential for the survival of aquatic animals and plants?
A: Gases from the atmosphere, especially oxygen and carbon dioxide, diffuse and dissolve in water and are essential for the survival of aquatic animals and plants.

 

Q: What is diffusion and how does it happen in different states of matter?
A: Diffusion is the intermixing of particles of two different types of matter on their own. It happens in different states of matter through the random movement of particles. In gases, the particles move about randomly at high speed, allowing for fast diffusion. In liquids, the particles move freely and have greater space between each other compared to solids, allowing for a higher rate of diffusion. In solids, the diffusion rate is lower due to the tightly packed particles.

 

Q: How do aquatic animals breathe under water?
A: Aquatic animals breathe under water due to the presence of dissolved oxygen in water. The oxygen dissolves in water and is absorbed by the animals through their gills, allowing them to survive underwater.

 

Q: What are some examples of compressed gases and how are they used?
A: Compressed gases include liquefied petroleum gas (LPG) used for cooking, compressed natural gas (CNG) used as fuel for vehicles, and compressed oxygen used in hospitals. They are compressed to reduce their volume for easier transportation.

 

Q: How does the property of diffusing differ between gases, liquids, and solids?
A: Gases show the property of diffusing very fast into other gases due to the high speed of particles and large space between them. Liquids have a higher rate of diffusion than solids due to the greater space between particles. In solids, the tightly packed particles result in a lower diffusion rate.

 

Q: What happens to the particles of a solid when its temperature is increased and it melts into a liquid?
A: When the temperature of a solid is increased, the kinetic energy of its particles also increases. The particles start vibrating with greater speed and the energy supplied by heat overcomes the forces of attraction between them. The particles leave their fixed positions and start moving more freely, resulting in the solid melting and becoming a liquid.

 

Q: What is the melting point and latent heat of fusion of a solid?
A: The melting point is the minimum temperature at which a solid melts to become a liquid at atmospheric pressure. The melting point of ice is 273.15 K. The latent heat of fusion is the amount of heat energy required to change 1 kg of a solid into a liquid at atmospheric pressure at its melting point. It is the heat energy absorbed by the solid during the process of melting, without showing any rise in temperature.

 

Q: What is the latent heat of vaporisation?
A: A:  The latent heat of vaporisation is the amount of heat energy required to change a substance from liquid to vapour at its boiling point, without a change in temperature.

 

Q: Why do we wear cotton clothes in summer?
A: We wear cotton clothes in summer because cotton is a good absorber of water, which helps in absorbing sweat and exposing it to the atmosphere for easy evaporation, thus keeping our body cool.

 

Q: Why do we see water droplets on the outer surface of a glass containing ice-cold water?
A: We see water droplets on the outer surface of a glass containing ice-cold water because the water vapour present in air, on coming in contact with the cold glass of water, loses energy and gets converted to liquid state, which we see as water droplets.

 

Q: How does the arrangement of particles differ in solids, liquids, and gases?
A: The arrangement of particles is most ordered in solids, in liquids layers of particles can slip and slide over each other, and in gases, there is no order, particles just move about randomly.

 

Q: What is the difference between boiling and evaporation?
A: Boiling is a bulk phenomenon, where particles from the bulk (whole) of the liquid change into vapor state, while evaporation is a surface phenomenon, where particles from the surface gain enough energy to overcome the forces of attraction present in the liquid and change into the vapor state.

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