# Matter in Our Surroundings Chapter 1 Class 9 Science Worksheets

Students should practice questions given in Matter in Our Surroundings Chapter 1 Class 9 Science Worksheets. These worksheets for Class 9 Science have a good collection of important questions and answers which are expected to come in your class tests and examinations. You should learn these solved worksheet questions for Science Class 9 as it will help you to understand all topics and give you more marks.

## Class 9 Science Worksheets Chapter 1 Matter in Our Surroundings

Please refer to below questions and answers for Matter in Our Surroundings Chapter 1 Class 9 Science Worksheets. Prepared by expert teachers for Standard 9 Science

Question. Name any two substances which sublime.

Camphor and naphthalene.

Question. Define condensation.

The change of solid state from liquid state on cooling is also known as condensation.

Question. What is plasma?

Plasma is a state of matter consisting of super excited particles of very high energy level.

Question. Which is the slow process, evaporation or boiling?

Evaporation.

Question. What is the effect of surface area on rate of evaporation?

If the surface area is increased, the rate of evaporation increases.

Question. Why is Kelvin scale of temperature regarded as better scale than Celsius?

As it has wide range of measurement and Kelvin scale of temperature has always positive sign, hence regarded as better scale than Celsius. Kelvin is an absolute thermodynamics scale, which uses its null point as the temperature at which all thermal motion ceases to exist.

Question. Define melting point.

The temperature at which a solid melts to become liquid at the atmospheric pressure is called its melting point.

Question. Convert 10°C into Kelvin scale.

273 + 10 = 283 K

Question. Why evaporation is called surface phenomenon?

Evaporation is called surface phenomenon as evaporation occur on the surface of liquid.

Question. When we put CuSO4 in water, after some time we find the solution turns blue. Why? Also, on heating it,what change will occur?

The solution turns blue because of diffusion. On heating the solution, nothing will happen.

Question. Does solid ice and liquid water co-exist together? If yes, then at what temperature?

At 0°C, the three phases of water co-exist called triple point.

Question. What is common among the three states of matter?

They all contain molecules.

Question. Which property of gas is used in supplying oxygen cylinders to hospitals?

Compressibility.

Question. A substance x is highly compressible and could easily be liquefied. It can also take the shape of the container.Guess the nature of the substance.

Gas.

Question. What is the significance of boiling point and melting point of a substance?

The significance of boiling point and melting point is that it shows the purity of the substance.

Question. When salt or sugar is poured into different kinds of vessels, why do they take the shape of vessel as they are solid?

Salt or sugar takes the shape of containing vessel, but does not change its individual shape. For example : Sugar crystal is cubical and they remain cubical in any vessel.

Question. Sponge is a solid, yet we are able to compress it. Why?

Sponge has very small holes throughout its structure.These holes are filled with air. When it is compressed,the air in the holes is squeezed out. Thus, we are able to compress it.

Question. How can you justify that table is a solid?

When we apply force on the table it doesn’t change its shape because its inter- molecules are tightly packed,this shows that table is solid.

Question. The Kelvin scale temperature is 0 K. What is the corresponding Celsius scale temperature?

–273°C

Question. A rubber band is a solid, but it can change its shape. Why?

A rubber band changes shape under force and regains the shape when the force is removed, this is due to less intermolecular force of attraction between the particles.

Question. State the effect of pressure on boiling point.

Boiling point increases with increase in pressure.

Question. What is the difference between a gas and plasma?
(i) Gas consist neutral particles which are associated with energies comparable with atmospheric temperature.
(ii) Plasma contains energetic particles in the form of ionized gases.

Question. What do you observe when force is applied and then removed on the plunger of the syringe containing air? Give a reason for your answer.
Answer. The plunger moves downward on the application of force to a considerable length. The plunger moves backward and takes its original position when the force is removed.
The gases have large intermolecular spaces. So,they easily get compressed on the application of force.The compressed gases are under high pressure. When the force is removed, this high pressure forces the plunger back to its original position.

Question. A piece of chalk can be broken into small pieces when hammered but it is not possible in case of iron bar.Why?
Answer. The force that keeps the particles together is lesser in chalk; hence it could be easily broken down into pieces on hammering. Whereas, the magnitude of this
intermolecular force is more in iron, hence it cannot be broken into small pieces on hammering.

Question. State characteristics of matter demonstrated by :
(i) Diffusion.
(ii) Brownian motion.
(i) Diffusion involves movement of different particles so that they become intermixed uniformly.
(ii) Brownian motion : It is the zig-zag movement of the small particles suspended in a liquid or a gas.

Question. What property of gas is used when natural gas is supplied for vehicles?
Answer. A gas is highly compressible and a large quantity of it can be compressed to a small, manageable volume.
Thus, natural gas is compressed and is supplied for use by vehicles in the name of CNG (compressed natural gas).

Question. Why is water liquid at room temperature?
Answer. At room temperature, the molecules of water have some intermolecular force of attraction and the room temperature cannot provide sufficient heat for these molecules to overcome their force of attraction and therefore, remain in liquid phase.

Question. A balloon when kept in Sun, bursts after some time. Why?
Answer. The balloon has air filled in it. The balloon when kept in Sun gets heated and the air inside it also gets heated. The molecules of air get energy, and vibrate faster thereby exerting large force on the walls of the balloon. Due to this expansion of gases the balloon

Question. How is pressure developed in a container full of a gas?
Answer. The gaseous particles are free to move in the container. These move at high speed and collide with other particles of the container. The bombardment of the particles on the walls of the container produces a steady force that depends on the temperature. This force per unit area is called as pressure of the gas.

Question. Why do people perspire a lot on a hot humid day?
Answer. On a hot humid day, due to the heat our body starts sweating and gives cooling effect by evaporation. But the air cannot hold any more water on a humid day and therefore, the sweat or perspiration is seen.

Question. On a hot sunny day, why do people sprinkle water on the roof or open grounds?
Answer. During hot sunny day, the surface of roof or ground absorbs large amount of heat and remains hot. On sprinkling water on these surfaces, the water absorbs large amount of heat from the surface of roof and water evaporates thereby causing cooling effect.

Question. Why is it advisable to use pressure cooker at higher altitudes?
Answer. At higher altitudes, the atmosphere pressure is low and the water boils very fast and evaporates at faster rate, therefore, the pressure is required to increase the cooking process and this is done by using pressure cooker which increases the pressure inside the container and cooks food faster.

Question. Why a rubber band is considered as a solid?
Answer. We can regard rubber band as a solid, because it regains its shape when the stretching force is removed from it.

Question. Both the process of evaporation and boiling involves the change of state from liquid to gas but still they are different from each other. Justify.
Answer. Evaporation is different from boiling as evaporation is a natural phenomenon, occurs on the surface of the water and also it is a slow process, whereas boiling is an artificial phenomenon, it occurs in the bulk of the liquid and is a fast process.

Question. Why is the smell of the perfume of incense stick filled the whole room in few minutes, when lighted?
Answer.When the incense stick is lighted, the heat energy makes the particles of the perfume to move rapidly.Thus, they easily drift through the air in the room and hence, we can smell it anywhere in the room.

Question. How is the high compressibility property of gas useful to us?
Answer. The gases have high compressibility. This property is used in the following situation :
(i) LPG (Liquefied Petroleum Gas) is a fuel which is made up of petroleum gas. On compressing this petroleum gas it forms liquid.
(ii) Oxygen cylinders in the hospitals have compressed gas filled in it.
(iii) CNG (Compressed Natural Gas) is a natural gas i.e. methane, which is compressed and used as a fuel in vehicles and at home.

Question. Discuss the factors which affect evaporation.
Answer. There are four factors which affect evaporation.
(i) Surface area : Escaping of particles from liquid state to vapour state depends on surface area.
Therefore, the rate of evaporation increases with surface area.
(ii) Temperature : Rise in temperature, rise the kinetic energy of substance and therefore, chance of escaping of particles is great from liquid to vapour state.
(iii) Wind : The rate of evaporation increases with speed of wind.
(iv) Humidity : Humidity is the amount of vapour present in the air. At fixed temperature air can’t hold more than fixed amount of water vapour.
Therefore, the evaporation rate decreases if humidity increases in air.

Question. With the help of an example, explain how diffusion of gases in water is essential?
Answer. The gases from the atmosphere diffuse and dissolve in water. Diffused gases like oxygen and carbon dioxide in water are essential for the survival of aquatic animals and plants. Animals breathe in this oxygen dissolved in water for their survival and plants can use carbon dioxide dissolved in water for photosynthesis.

Question. The melting point of ice is 273.16 K. What does this mean? Explain in detail.
Answer. Ice is solid at 0°C, i.e. 273 K. The molecules of ice are tightly packed. These molecules have to overcome the force of attraction with which they are held and hence, they gain this heat from the surrounding but the temperature remains the same as their energy is used to overcome the force of attraction between the particles. The particles of ice start vibrating freely and a stage reaches when the solid ice melts and is converted to liquid state at the same temperature,i.e. 273 K.