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CBSE Questions for Class 9 Chemistry Matter In Our Surroundings Quiz 5 - MCQExams.com
CBSE
Class 9 Chemistry
Matter In Our Surroundings
Quiz 5
Conversion of a liquid into vapour form at any temperature below its boiling point is called as ______________.
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solidification
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gasification
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evaporation
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liquifaction
Explanation
In the case of liquids, a small fraction of particles at the surface, having higher kinetic energy, can break away from the forces of attraction of other particles and gets converted into vapour. The conversion of a liquid into vapours at any temperature below its boiling point is called evaporation.
The rate of evaporation increases with:
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increase of surface area
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increase of temperature
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increase in wind speed
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all of above
Explanation
If the surface area is increased, the rate of evaporation increases. With the increase of temperature, more number of particles get enough kinetic energy to go into the vapour state. With the increase in wind speed, the particles of water vapour move away from the wind, decreasing the amount of water vapour in the surrounding.
So, option $$D$$ is correct.
In liquids, there is ____________ and ____________ between particles.
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strong force of attraction, more spacing
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weaker force of attraction, more spacing
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weaker force of attraction, less spacing
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strong force of attraction, less spacing
Explanation
Liquids have no fixed shape but have a fixed volume. They take up the shape of the container in which they are kept. In liquids, there is a weaker force of attraction and more spacing between the particles.
Hence, they are not rigid and can flow.
Why do clothes dry faster on a windy day?
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Evaporation increases with increase in wind speed.
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Evaporation increases with increase in humidity.
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Evaporation decreases with increase in wind speed.
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None of these
Explanation
Evaporation increases with increase in wind speed. With the increase in wind speed, the particles of water vapour move away with the wind, decreasing the amount of water vapour in the surrounding. Hence, clothes dry faster on a windy day.
While mixing sugar with water, the level of water does not increase because _____________.
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matter has large particles which destroy water particles
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tiny particles of sugar adjust among the space between tiny particles of water
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tiny particles of sugar destroy large particles of water
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None of the above
Explanation
While mixing sugar with water, the level of water does not increase because tiny particles of sugar adjust among the space between tiny particles of water. This shows that space is present between the molecules of liquids.
The presence of a significant number of charge carriers makes plasma as _____________.
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electrically conductive
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non-conductive
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ductile
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compressible
Explanation
Plasma is one of the four fundamental states of matter, the others being solid, liquid, and gas. The presence of a significant number of charge carriers makes plasma electrically conductive, so that it responds strongly to electromagnetic fields.
While putting clothes for drying up, why do we spread them out?
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Surface area is directly proportional to rate of evaporation.
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Increase in surface area decreases rate of evaporation.
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Increase in surface area increases rate of evaporation.
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Both A and C.
Explanation
Evaporation is a surface phenomenon. If the surface area is increased, the rate of evaporation increases. While putting clothes for drying up, we spread them out, because, more area is exposed to sun and wind which speeds up the rate of evaporation.
What is the effect of pressure on gas?
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Volume of gas decreases with increase in pressure
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Volume of gas increases with increase in pressure
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Both a and b
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Pressure has no effect on gas
Explanation
The volume of gas decreases with an increase in pressure. This leads to the conversion of the gaseous state into a liquid state and eventually into a solid-state.
The volume of the gas decreases by applying pressure on gases because gases are compressible.
What is latent heat of vaporization?
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Heat absorbed when a substance changes phase from solid to gas.
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Heat absorbed when a substance changes phase from liquid to gas.
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Heat released when a substance changes phase from liquid to gas.
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Heat absorbed when a substance changes phase from gas to liquid.
Explanation
Latent heat of vaporization is the amount of heat absorbed when 1 kg of liquid changes into vapor at constant temperature. When a liquid vaporize at the normal boiling point the temperature of the liquid will not rise beyond the temperature of the boiling point.
Evaporation that occurs directly from the solid phase below the melting point is called as:
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Sublimation
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condensation
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distillation
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None of above
Explanation
Evaporation occurs directly from the solid phase below the melting point, as commonly observed with the Sublimation of ammonium chloride.
Evaporation of water will be faster:
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near the sea
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far away from the sea
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both at equal rates
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None of the above
Explanation
An increase in humidity reduces the rate of evaporation. Area near the sea will be more humid as compared to the area far away from the sea. Hence, evaporation will be faster away from the sea.
Coolers are more effective in areas with ___________.
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low humidity
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high humidity
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both A and B
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none of above
Explanation
A decrease in humidity increases the rate of evaporation. Coolers work on the concept of evaporation.
Evaporation causes cooling when liquid particles absorb energy from the surroundings to regain the lost energy during evaporation. This absorption of energy from surrounding cools the area.
In high humid areas, the rate of evaporation is low and making cooler not very effective. On the other hand, in low humid areas, the rate of evaporation is high which causes cooling and thus, coolers are more effective in such areas.
The state or phase of a given set of matter can change depending on _____________.
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temperature
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pressure
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Both a and b
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None of above
Explanation
The state or phase of a given set of matter can change depending on pressure and temperature conditions, transitioning to other phases as these conditions change to favor their existence; for example, solid transitions to liquid with an increase in temperature. When pressure increases on a substance in a gas phase it can cause the substance to be condensed or a decrease in pressure on the substance can cause it to vaporize.
Hence, option $$C$$ is correct.
When liquid takes up heat from the surrounding, the surrounding ____________.
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cools down
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heats up
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remains unchanges
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None of above
Explanation
Liquid requires latent heat of vaporization. So, when the liquid takes up the heat from the surrounding to vaporize, the temperature of surrounding reduces, and it cools down due to loss of heat.
Why do we wear cotton clothes in summer?
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Cotton absorbs water
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It leads to sweating
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Both a and b.
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None of above
Explanation
Cotton absorbs water, and thus, causes sweating. Sweat comes out the clothing and in contact with the atmosphere. It evaporates taking up the heat from the surrounding and thus, gives a cooling effect.
A volatile liquid _____________.
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vaporizes quickly at room temperature
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solidifies quickly at room temperature
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liquifies quickly at room temperature
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does not vaporize quickly
Explanation
A volatile liquid is one that evaporates or vaporizes quickly at room temperature. Volatile liquids have low boiling point. As a result, they evaporate very easily at room temperature.
Spacing between particles of gas can be decreased. Hence, __________.
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they have no compressibility
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they are rigid
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they have compressibility
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None of above
Explanation
Spacing between particles of gas can be can be decreased by increasing pressure. Hence, gases have high compressibility. Solids and liquids are not compressible as the spacing between their particles cannot be decreased.
Which of the following factor can affect evaporation?
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High pressure on liquid surface
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Specific heat
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Latent energy
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All of above
Explanation
Evaporation is the surface phenomenon in which if high pressure is present on the surface of the liquid, it reduces the rate of evaporation.
Storms are examples of high-pressure systems that slow down evaporation.
Therefore, the option is $$A$$.
Three containers X, Y and Z as shown were filled with water and then left near an open window. The purpose was to find out whether the exposed surface area of the water affects the rate of evaporation of water. Why was the experiment NOT a fair one?
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The exposed surface areas were different
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Different types of containers were used
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The amount of water in the containers was different
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The containers were not covered
Explanation
The rate of evaporation is affected by the exposed surface area of water.
Higher the exposed surface area, the higher the rate of evaporation.
The experiment is not a fair one because the amount of water in the content are different.
The inter-particle attractive force ______ with increasing distance between particles.
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increases
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decreases
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does not change
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None of the above
Explanation
As the distance between the particles reduces, it means they will be held together weakly. Consequently, the force of attraction between the particles decreases.
Hence, the correct option is B.
Which of the following has a direct effect on the kinetic energy of particles?
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Pressure
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Potential energy
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Temperature
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All of the above
Explanation
When the temperature of a substance is increased collision, rate between particles increases which increases the speed of particles which implies that the kinetic energy of particles is directly proportional to the temperature of the substance.
Evaporation is a _______ phenomenon.
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surface
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bulk
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solid
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none
Explanation
$$Surface$$ phenomenon is a process in which only the surface of any substance or object is involved in the process. In Evaporation only the surface of the liquid involves in the process, its bulk remains unaffected by evaporation. Hence, it is a surface phenomenon.
Based on the statements given below, choose the correct answer.
P: Some sugar can be added to a glass full of water without causing an overflow.
Q: Liquids have spaces present between the molecules.
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P and Q are true and Q explains P
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P and Q are true but Q does not explain P
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Only P is true
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Only Q is true
Explanation
Liquids have indefinite shape. They have weak interparticle forces of attraction, so they are not closely packed. They have empty spaces between the particles. When small amount of sugar is added, the sugar particles occupy these empty spaces and do not cause an overflow of the water.
Hence, P and Q are true and Q correctly explains P.
The process by which molecules undergo a spontaneous transition from the liquid phase to the gaseous phase is called as:
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freezing
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sublimation
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evaporation
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condensation
Explanation
Evaporation is a process by which molecules undergo a spontaneous transition from the liquid phase to the gaseous phase.
Freezing is a phase transition where a liquid turns into a solid.
Sublimation is the conversion between the solid and the gaseous phases of matter, with no intermediate liquid stage.
Condensation is the reverse of evaporation in which water vapour converts into liquid water.
__________ of ice is the energy that is used to change the state of ice to water.
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Latent heat of fusion
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Latent heat of vaporization
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Conduction
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All of above
Explanation
When solid changes into a liquid, the heat required for changing the state without rising in temperature is called latent heat of fusion.
The $$\text {latent heat of fusion}$$ of ice is the energy that is used to change the state of ice (solid) to water (liquid).
Option $$A$$ is correct.
Which of the following represents true statement(s)?
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Solids will not break under force.
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It is easy to change shape of solids as they are highly compressible.
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Both of the above
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None of the above
Explanation
Solids are breakable when force applied. They are least compressible hence are rigid thus shape cannot be changed. None of the above statements are true.
State whether true or false :
Sponge is also solid. Yet we are able to compress it.
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True
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False
Explanation
A sponge is a solid that can be easily compressed. Sponge has minute holes in which air is trapped. When we press it, the air is expelled and we are able to compress it.
So, the given statement is true.
Evaporative cooling is the phenomenon _____________.
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in which molecule of liquid with high kinetic energy evaporates quickly, leaving behind the particle of less kinetic energy
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in which molecule of liquid with low kinetic energy evaporates quickly, leaving behind the particle of high kinetic energy
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in which density of liquid changes
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none of these
Explanation
Evaporation is the surface phenomenon in which the liquid molecules that have high kinetic energy evaporates quickly from the surface of the liquid. Thus the molecules with less kinetic energy remain in the solution and, as result the temperature of the liquid decreases. This phenomenon is known as evaporative cooling.
Evaporation of water in shade is:
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No evaporation takes place in shade
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faster
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slower
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None of these
Explanation
Evaporation of water in shade is slower, as the sun's heat increases the energy of water molecules, and they start moving faster, eventually leading to evaporation when the energy is enough to convert into a vapour.
Which of the following arrangement represents a liquid?
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I
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II
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III
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All of the above
Explanation
In liquid, the inter-particle space is intermediate. This means the inter-particle space of liquid is more than solid but less than gas.
From the given diagram $$\text{I}$$ represents gas, $$\text {II}$$ represents liquid and $$\text {III}$$ is solid.
Hence, option $$B$$ is correct.
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