Mix Examples - MATTER IN OUR SURROUNDINGS Questions in English

(N/A) Density is defined as the mass per unit volume of a substance. Generally, the density of states of matter follows the order: $Gas < Liquid < Solid$.
$1$. Air and exhaust from chimneys are gases, which have the lowest density.
$2$. Water and honey are liquids, which have a higher density than gases.
$3$. Cotton, chalk, and iron are solids, which have the highest density.
Within these categories, the specific order of increasing density is:
Air < Exhaust from chimneys < Cotton < Water < Honey < Chalk < Iron.

(N/A) $Rigidity$: The property by which an object retains its shape and size is called rigidity. Solids are rigid, whereas liquids and gases are not.
$Compressibility$: This is the property due to which a substance can be compressed, meaning its volume can be decreased. Gases are highly compressible, whereas solids and liquids are generally considered incompressible.
$Fluidity$: The tendency of a substance to flow is called fluidity. Gases and liquids are fluids, while solids are not.
$Filling \text{ } a \text{ } gas \text{ } container$: $A$ large volume of gas can be filled into a small container by compressing it under very high pressure. This is possible due to the high compressibility of gases.
$Shape$: The property of having a definite geometry is called the shape of a substance. Solids have a definite shape, whereas liquids and gases take the shape of the container.
$Kinetic \text{ } energy$: The energy possessed by moving particles or molecules is called kinetic energy. On increasing the temperature, the kinetic energy of molecules increases. Gas molecules possess the highest kinetic energy.
$Density$: The mass per unit volume of a substance is called density. Density = $\frac{\text{Mass}}{\text{Volume}}$.

(A) $1$. Evaporation: The rate of evaporation increases with an increase in temperature because particles gain more kinetic energy to overcome intermolecular forces.
$2$. Diffusion: As temperature increases,the kinetic energy of particles increases,leading to faster movement and higher rates of diffusion.
$3$. Expansion of gases: Gases expand when heated because the kinetic energy of the gas particles increases,causing them to move further apart.
$4$. Compression of gases: Compression decreases as temperature increases because the particles move faster and exert more pressure,making them harder to compress.
Therefore,the set of phenomena that increases with temperature is evaporation,diffusion,and expansion of gases.

(B) The distance between gas molecules increases when the density of the gas decreases or the available space for the molecules increases.
$(i)$ Increasing pressure forces molecules closer together,decreasing the distance.
$(ii)$ If some hydrogen gas leaks out,the number of molecules decreases while the volume remains the same,leading to an increase in the average distance between the remaining molecules.
$(iii)$ Increasing the volume of the container allows the same number of molecules to spread out over a larger space,thereby increasing the average distance between them.
$(iv)$ Adding more hydrogen gas increases the number of molecules in the same volume,which decreases the distance between them.
Therefore,conditions $(ii)$ and $(iii)$ lead to an increase in the distance between molecules.

(D) Since ice and water are in equilibrium,the initial temperature of the mixture is $0^{\circ}C$. When we heat the mixture,the energy supplied is utilized in melting the ice (phase change from solid to liquid). During this process,the temperature does not change until all the ice has melted because of the latent heat of fusion. Once all the ice has melted,further heating causes the temperature of the water to increase. Therefore,graph $(d)$ correctly represents this process,as it shows a constant temperature at $0^{\circ}C$ for some time followed by an increase in temperature.

(N/A) cooling
$(b)$ stronger
$(c)$ liquid,gaseous
$(d)$ sublimation,liquid
$(e)$ evaporation

(B) The correct matching of physical quantities with their $SI$ units is as follows:
$(a)$ Pressure: The $SI$ unit of pressure is the pascal $(Pa)$, which corresponds to $(iii)$.
$(b)$ Temperature: The $SI$ unit of temperature is the kelvin $(K)$, which corresponds to $(iv)$.
$(c)$ Density: Density is defined as mass per unit volume, so its $SI$ unit is kilogram per cubic metre $(kg/m^3)$, which corresponds to $(v)$.
$(d)$ Mass: The $SI$ unit of mass is the kilogram $(kg)$, which corresponds to $(ii)$.
$(e)$ Volume: The $SI$ unit of volume is the cubic metre $(m^3)$, which corresponds to $(i)$.
Therefore, the correct sequence is $(a) - (iii), (b) - (iv), (c) - (v), (d) - (ii), (e) - (i)$.

(C) The correct matches are as follows:
$(a)$ Degree Celsius is a unit of temperature, and its $SI$ unit is Kelvin $(iv)$.
$(b)$ Centimeter is a unit of length, and its $SI$ unit is metre $(iii)$.
$(c)$ Gram per centimetre cube is a unit of density, and its $SI$ unit is kilogram per metre cube $(v)$.
$(d)$ Bar is a unit of pressure, and its $SI$ unit is pascal $(ii)$.
$(e)$ Milligram is a unit of mass, and its $SI$ unit is kilogram $(i)$.
Therefore, the correct sequence is $(a)-(iv), (b)-(iii), (c)-(v), (d)-(ii), (e)-(i)$.

(N/A) Osmosis: Water enters the raisin due to a higher water concentration outside.
$(b)$ Diffusion: Virus particles move from a region of higher concentration to lower concentration in the air.
$(c)$ Osmosis: Water moves out of the earthworm's body due to the high salt concentration outside (exosmosis).
$(d)$ Osmosis: Water moves out of the grapes into the hypertonic sugar syrup.
$(e)$ Osmosis: Salt creates a hypertonic environment,causing water to move out of the cells of the pickles (exosmosis).
$(f)$ Diffusion: Aroma molecules move from the cake to the surrounding air.
$(g)$ Diffusion: Dissolved oxygen moves from water into the aquatic animal's body across the respiratory surface.

(A) The correct answer is $(a)$.
When hot water is placed in a freezer,it loses heat to the surroundings and its temperature decreases until it reaches $0\,^{\circ}\text{C}$.
At $0\,^{\circ}\text{C}$,the water begins to undergo a phase change from liquid to solid (ice). During this phase transition,the temperature remains constant at $0\,^{\circ}\text{C}$ because the heat being removed is used as latent heat of fusion.
Once all the water has frozen into ice,the temperature of the ice will continue to decrease further below $0\,^{\circ}\text{C}$ as it continues to lose heat to the freezer environment.
Graph $(a)$ correctly depicts this cooling curve: a steady decrease,a horizontal plateau at $0\,^{\circ}\text{C}$ during freezing,and a further decrease after the phase change is complete.

(N/A) Evaporation produces cooling because the particles at the surface of the liquid gain energy from the surroundings to overcome the forces of attraction and change into vapour,thereby absorbing heat and producing a cooling effect.
$(b)$ Humidity is the amount of water vapour present in the air. Air can hold only a definite amount of water vapour at a given temperature. If the humidity is already high,the air cannot hold more water vapour,which decreases the rate of evaporation.
$(c)$ $A$ sponge has minute holes in which air is trapped. When we press it,the air is expelled out,allowing it to be compressed. Despite this,it is considered a solid because it has a definite shape and volume when not subjected to external force.

(N/A) Naphthalene is a substance that undergoes sublimation,meaning it changes directly from a solid to a gas without passing through the liquid state. As it absorbs heat from the surroundings,the naphthalene balls sublime and disappear over time.
$(b)$ The smell of perfume is due to the presence of volatile aromatic compounds. These particles diffuse rapidly through the air,allowing us to detect the scent even when sitting several metres away.

(N/A) sponge has minute holes in which air is trapped. On applying pressure or force,the air is expelled out and the sponge gets compressed. On releasing the pressure,the sponge regains its shape. Thus,a sponge is classified as a solid.
$(b)$ $(i)$ In the gaseous state,particles have high kinetic energy,which allows them to move freely and maintain large spaces between them.
$(ii)$ Therefore,the particles occupy the entire space available. Hence,gases completely fill the vessel in which they are kept.

(N/A) $(i)$ The level of water remains almost the same because the particles of Dettol occupy the spaces between the water particles.
$(ii)$ $A$ colloidal solution is formed,not a true solution,as Dettol particles are dispersed in water.
$(iii)$ The water turns milky white due to the formation of an emulsion.
$(iv)$ The characteristic smell of Dettol can be detected even after repeated dilution,which demonstrates that matter is made up of very small particles.

(A) $(i)$ Liquid: Liquids are incompressible and take the shape of the container,meaning they have no fixed shape.
$(ii)$ Solid: Solids are incompressible and generally have high melting points due to strong intermolecular forces.
$(iii)$ Gas: Gases are highly compressible and do not have a definite volume or shape.
$(iv)$ Liquid: Liquids are incompressible and exhibit high fluidity,allowing them to flow easily.

(N/A) $(i)$ $(a)$ $LPG$: Liquefied Petroleum Gas.
$(b)$ $CNG$: Compressed Natural Gas.
$(ii)$ $(a)$ $LPG$ is used as a domestic fuel for cooking.
$(b)$ $CNG$ is used as a clean fuel in automobiles and vehicles.

(A) Formation of clouds occurs due to the process of condensation,where water vapor cools down to form liquid water droplets.
$(b)$ Drying of wet clothes occurs due to evaporation,where water changes into water vapor at room temperature.
$(c)$ Wax melting in the sun is an example of fusion (melting),where a solid changes into a liquid state upon heating.
$(d)$ The size of naphthalene balls decreases due to sublimation,where a solid directly changes into a gaseous state without passing through the liquid phase.

(A) : Fusion (melting) - The process of conversion of a solid into a liquid.
$B$: Vaporisation - The process of conversion of a liquid into a gas.
$C$: Condensation - The process of conversion of a gas into a liquid.
$D$: Sublimation - The process of conversion of a solid directly into a gas.

(N/A) $CO_{2}$ has neither a fixed volume nor a fixed shape,which is a characteristic property of gases.
It exerts pressure on the walls of its container due to the random collisions of its molecules.
$CO_{2}$ can be liquefied by applying high pressure and lowering the temperature.
Solid $CO_{2}$ is known as dry ice because it undergoes sublimation,meaning it converts directly from a solid state to a gaseous state at atmospheric pressure without passing through the liquid phase.

(N/A) Liquefaction of gases,such as the compression of $LPG$ (Liquefied Petroleum Gas) into cylinders.
$(b)$ The two factors determining the rate of diffusion are:
$(i)$ Temperature: The rate of diffusion increases with an increase in temperature because the kinetic energy of the particles increases.
$(ii)$ Concentration/Density: The rate of diffusion decreases as the concentration or density of the liquid increases.

(N/A) The temperature at which a liquid starts boiling at atmospheric pressure is called its boiling point.
$(b)$ The boiling point of water is $100^{\circ}C$ on the Celsius scale and $373 K$ on the Kelvin scale.
$(c)$ This observation shows that the particles of matter have spaces between them,which allows the diver to move through the water.

(N/A) $(i)$ Liquid molecules are able to slide over one another due to slightly weaker intermolecular forces of attraction compared to solids,allowing them to flow.
$(ii)$ This is due to the latent heat of fusion. Ice at $0^{\circ} C$ absorbs additional heat energy from the mouth to change its state into water at $0^{\circ} C$. Therefore,it feels colder than water at the same temperature.
$(iii)$ Water,while evaporating,absorbs the necessary latent heat of vaporization from the patient's body,which helps in lowering the body temperature.

(N/A) $(i)$ Gas particles move randomly at high speeds and collide with the walls of the container,exerting force per unit area,which is perceived as pressure.
$(ii)$ Water is a liquid at room temperature because its melting point is below room temperature $(0 \ ^\circ C)$ and its boiling point is above room temperature $(100 \ ^\circ C)$.
$(iii)$ During evaporation,particles of the liquid absorb energy from the surroundings to overcome the forces of attraction and change into the vapor state. This loss of energy from the surroundings results in a cooling effect.

(N/A) Anything which has mass and occupies space is called matter.
Three states are: Solid,liquid,and gaseous.
$(b)$ These states arise due to variation in the characteristics of the particles,specifically:
$(i)$ Interparticle space: The distance between particles is minimum in solids,more in liquids,and maximum in gases.
$(ii)$ Interparticle force of attraction: The force is strongest in solids,moderate in liquids,and weakest in gases.
$(iii)$ Kinetic energy of the particles: The kinetic energy is minimum in solids and maximum in gases,which influences the movement of particles.

(N/A) Matter is anything that has mass,occupies space,and has volume.
Properties of solids: $(1)$ They have a definite shape and distinct boundaries. $(2)$ They have a fixed volume and negligible compressibility.
Properties of liquids: $(1)$ They do not have a fixed shape but take the shape of the container. $(2)$ They have a definite volume and can flow (fluidity).
$(b)$ Observation: The water in beaker $A$ (hot water) becomes coloured faster than the water in beaker $B$ (cold water).
Reason: Diffusion is the movement of particles from a region of higher concentration to a region of lower concentration. At higher temperatures,the kinetic energy of the water particles increases,which causes the particles of copper sulphate to diffuse more rapidly throughout the water.

(N/A) Particles of sugar crystals occupy the empty spaces between the particles of water,hence the volume does not increase significantly.
$(b)$ The water in the wet cloth absorbs excess heat from the body due to the high latent heat of vaporisation,which helps in lowering the body temperature.
$(c)$ Naphthalene balls undergo sublimation,where they directly convert from a solid state to a gaseous state without leaving any residue.
$(d)$ $A$ wooden table has a fixed shape,a fixed volume,and is rigid and incompressible,which are the characteristic properties of a solid.
$(e)$ Dogs hang out their tongues to increase the surface area for the evaporation of saliva,which causes a cooling effect on their body.

(N/A) Activity:
$(i)$ Take $2-3$ crystals of copper sulphate and dissolve them in $100\, mL$ of water.
$(ii)$ Take out approximately $10\, mL$ of this solution and put it into $90\, mL$ of clear water.
$(iii)$ Take out $10\, mL$ of this solution and put it into another $90\, mL$ of clear water.
$(iv)$ Keep repeating this process of dilution.
Observation:
$A$ crystal of copper sulphate contains millions of tiny particles which keep on dividing into smaller and smaller numbers with each dilution. This shows that particles of matter are very small.
$(b)$ Matter is anything that has mass and occupies space.
$(i)$ Solid: The forces between constituent particles are strongest in solids.
$(ii)$ Gas: The forces between constituent particles are weakest in gases.
$(c)$ Yes,sugar and common salt are solids. Although they take the shape of the container they are kept in,the shape of each individual crystal remains fixed. Therefore,they are considered solids.

(N/A) The comparison is as follows:

Property	Block of wood	Water	Air
$(i)$ Compressibility	Negligible	Very low	High
$(ii)$ Particle motion	Least (vibratory only)	More than wood	Very high (random)
$(iii)$ Rigidity	Rigid	Fluid	Fluid

$(b)$ $(i)$ Gases exert pressure on the walls of the container because gas particles are in constant random motion at high speeds. When they collide with the walls of the container,they exert a force per unit area,which is perceived as pressure.
$(ii)$ Liquids are called fluids because they have the ability to flow and change their shape according to the container they are placed in,which is a characteristic property of fluids.

(N/A) $(i)$ Force of attraction: $\text{Oxygen gas} < \text{Kerosene} < \text{Iron nail}$.
$(ii)$ Intermolecular space: $\text{Iron nail} < \text{Kerosene} < \text{Oxygen gas}$.
$(b)$ $(i)$ Rigidity: It is the property of matter to maintain its shape against an external force.
$(ii)$ Compressibility: It is the property of matter by virtue of which its particles can be brought closer to each other under pressure.
$(iii)$ Diffusion: The spontaneous intermixing of particles of different types of matter due to their motion is known as diffusion.

(A) $(i)$ Rigidity: The property of matter to maintain its shape even when an external force is applied.
$(ii)$ Compressibility: The property of matter by virtue of which its particles can be brought closer to each other by applying external pressure.
$(iii)$ Density: The mass per unit volume of a substance,defined as $\text{Density} = \frac{\text{Mass}}{\text{Volume}}$.

Property	Solid	Liquid	Gas
Rigidity	Rigid	Fluid	Fluid
Compressibility	Negligible	Very low	High
Density	High	Less than solids	Least

(A) The properties are arranged in descending order (from highest to lowest) as follows:
$(a)$ Kinetic energy: Particles in gases have the highest kinetic energy due to large intermolecular spaces and high speed, followed by liquids, and then solids. Thus, the order is: $Hydrogen (gas) > Water (liquid) > Honey (viscous liquid/solid-like)$.
$(b)$ Density: Density is defined as mass per unit volume. Solids/viscous liquids are more compact than liquids, which are more compact than gases. Thus, the order is: $Honey > Water > Hydrogen$.

(N/A)

Diffusion	Osmosis
$1$. This process can take place in any medium (solid,liquid,or gas).	$1$. This process occurs only in a liquid medium.
$2$. The molecules undergoing diffusion may be in solid,liquid,or gaseous state.	$2$. Only solvent molecules (usually water) undergo osmosis.
$3$. It can occur without or through a semipermeable membrane.	$3$. It always takes place through a semipermeable membrane.
$4$. This process depends on the kinetic energy of the molecules participating.	$4$. This process involves the movement of solvent molecules from a region of higher water potential to a region of lower water potential.
$5$. It establishes an equilibrium in the concentration of molecules throughout the medium.	$5$. It does not necessarily equalize the concentration of solutes on both sides of the membrane.