Mix Example - MATTER IN OUR SURROUNDINGS Questions in English

(N/A) Gases have large interparticle spaces and no fixed shape or volume,which justifies that $CO_2$ is a gas.
$(b)$ $A$ gas can be liquefied by increasing the pressure and decreasing the temperature,which brings the particles closer together.
$(c)$ Solid $CO_2$ is called dry ice because it undergoes sublimation,meaning it converts directly from a solid state to a gaseous state without passing through the liquid phase.
$(d) (i)$ $CNG$: Compressed Natural Gas.
$(ii)$ $LPG$: Liquefied Petroleum Gas.

(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) During evaporation,a small fraction of particles at the surface having higher $KE$ (Kinetic Energy) is able to break away from the force of attraction of other particles and gets converted into vapour.
$(b)$ $(i)$ Rate of evaporation increases with temperature because an increase in temperature provides more $KE$ to the particles,allowing more particles to escape the surface.
$(ii)$ Rate of evaporation increases with wind speed because the moving air carries away the water vapour particles,thereby decreasing the concentration of water vapour in the surrounding area.
$(iii)$ Rate of evaporation decreases with humidity because the air is already saturated with water vapour,leaving less space for additional water molecules to evaporate.

(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.

(N/A) Similarity: In both processes,a liquid is converted into vapours.
Difference: Evaporation is a surface phenomenon,whereas boiling is a bulk phenomenon.
$(b)$ $(i)$ Cotton is a good absorber of water. It absorbs perspiration from our body and exposes it to the atmosphere for evaporation,which causes a cooling effect.
$(ii)$ $A$ wet handkerchief placed on the forehead absorbs heat from the body as the water evaporates. This process of evaporation causes cooling,which helps in lowering the body temperature.
$(iii)$ During the rainy season,the humidity in the atmosphere is high. Since the air is already saturated with water vapours,the rate of evaporation decreases,causing wet clothes to dry slowly.

(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 melting point of a solid is a measure of the strength of the forces of attraction between the constituent particles (atoms,ions,or molecules) of the solid.
$A$ higher melting point indicates that the particles are held together by stronger forces of attraction,requiring more energy (heat) to overcome these forces and transition the substance from a solid state to a liquid state.

(A) Steam at $373 \, K$ will cause more severe burns.
This is because steam contains additional energy known as the latent heat of vaporization.
At $373 \, K$,water molecules in the steam state have absorbed extra heat to change their phase from liquid to gas.
When steam comes into contact with the skin,it releases this latent heat along with its thermal energy,resulting in more severe burns compared to water at the same temperature.

(N/A) Solid $CO_2$ is known as dry ice. It is called dry ice because,at a constant pressure of $1 \text{ atmosphere}$,solid $CO_2$ undergoes sublimation,meaning it converts directly from a solid state to a gaseous state without passing through the liquid phase.

(B) To liquefy gases,the following two physical quantities must be altered:
$(i)$ Pressure is increased: Increasing pressure brings the gas particles closer together,which decreases the interparticle space.
$(ii)$ Temperature is reduced: Decreasing the temperature reduces the kinetic energy of the particles,which increases the interparticle forces of attraction,allowing the gas to condense into a liquid state.

(N/A) $(i)$ The molecules of a gas are in constant,random motion in all directions. As they move,they collide with each other and strike the walls of the container,exerting a force per unit area,which is perceived as pressure.
$(ii)$ The force of attraction between the particles of a gas is negligible,and the particles possess high kinetic energy. This allows them to move freely and occupy all the available space in the vessel in which they are kept.

(N/A)

Variation in Characteristic	Effect on State of Matter
$(i)$ Temperature	With an increase in temperature,the solid state melts to form a liquid,and a liquid boils to form a gaseous state.
$(ii)$ Pressure	With an increase in pressure,the gaseous state liquefies,and liquids can be compressed further.
$(iii)$ Interparticle space	The space between particles is minimal in solids,moderate in liquids,and maximum in gases,determined by temperature and pressure.
$(iv)$ Interparticle forces	Strongest in solids,weaker in liquids,and negligible in gases,which dictates the physical state.
$(v)$ Kinetic energy	Higher kinetic energy at higher temperatures leads to the transition from solid to liquid to gas.

(N/A) During the process of evaporation,the particles of the liquid absorb energy from the surroundings to overcome the force of attraction and change into the vapour state. This absorption of energy from the surroundings makes the surroundings cold.
$(b)$ An earthen pot has a large number of extremely small pores on its surface. Water continuously seeps out through these pores and evaporates. The energy required for this evaporation is taken from the remaining water inside the pot. As the heat is lost from the water,it cools down.

(N/A) $(i)$ Oxygen has neither a fixed shape nor a fixed volume,which is a characteristic property of gases.
$(ii)$ Oxygen particles have high kinetic energy and large intermolecular spaces,allowing it to diffuse easily into the air.
$(iii)$ Oxygen exerts pressure on the walls of its container and can be compressed or liquefied under high pressure and low temperature.

(N/A) The state of matter in which layers of particles can slip and slide over one another easily is the liquid state. In liquids,the intermolecular forces are weaker than in solids,allowing particles to flow.
$(b)$ The state of matter in which particles move around randomly due to very weak forces of attraction is the gaseous state. In gases,the intermolecular forces are negligible,allowing particles to move freely and randomly in all directions.

(N/A) The physical state of matter can be changed by increasing or decreasing the pressure applied to it.
For example,a gas can be liquefied by applying high pressure. This occurs because,under high pressure,the molecules of the gas are forced to come closer to each other,which increases the intermolecular forces of attraction,thereby converting the gas into a liquid state.

(B) The correct order of temperature is $T_C < T_B < T_A$.
Reason: The kinetic energy of particles is directly proportional to the absolute temperature of the substance. As the temperature increases,the kinetic energy of the particles also increases. Since the given kinetic energies follow the order $E_A > E_B > E_C$,the corresponding temperatures must follow the same order,$T_A > T_B > T_C$. Therefore,in increasing order,the temperatures are $T_C < T_B < T_A$.

(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) Latent heat of fusion is the amount of energy required to change $1 \, kg$ of a solid into a liquid at its melting point.
During the process of melting ice,the heat supplied is used up in changing the state of the substance by overcoming the forces of attraction between the particles. Since this energy is consumed to break the intermolecular bonds rather than increasing the kinetic energy of the particles,the temperature does not rise and remains constant.

(N/A) Steam contains water particles that possess high kinetic energy due to the latent heat of vaporization. When steam comes in contact with the skin,it releases this extra heat energy,causing severe burns.
Conversely,in the case of ice,the water particles possess lower energy. When ice comes in contact with the skin,it absorbs heat energy from the surroundings (or the body) to undergo a phase change from solid to liquid,thereby producing a cooling effect.

(N/A) Solid state: Solids have a rigid structure,resulting in a definite shape,volume,and mass.
$(b)$ Gaseous state: In gases,particles are far apart with negligible intermolecular forces,leading to the minimum force of attraction.
$(c)$ Solid state: In solids,particles are closely packed with strong intermolecular forces,resulting in the maximum force of attraction.

(C) The interconversion of the states of matter can be achieved in the following two ways:
$(i)$ By changing the temperature: Increasing or decreasing the temperature can cause a substance to change its state (e.g.,melting of ice into water or freezing of water into ice).
$(ii)$ By changing the pressure: Increasing or decreasing the pressure can also change the state of matter,especially in gases (e.g.,liquefaction of gases by applying high pressure and lowering the temperature).

(N/A) The melting point is defined as the temperature at which a solid substance changes its state from solid to liquid at atmospheric pressure.
Fusion is the physical process of a substance changing from a solid state to a liquid state.
In scientific terminology,melting and fusion refer to the exact same process of phase transition from solid to liquid.

(N/A) During the change of state,the heat energy supplied is used up in overcoming the force of attraction between the particles of the substance. This energy is known as latent heat. Since this energy does not increase the kinetic energy of the particles,the temperature of the substance remains constant during the phase transition.

(N/A) Evaporation is the phenomenon of the change of a liquid into vapours at any temperature below its boiling point.

Evaporation	Boiling
$1.$ Evaporation occurs on its own at all temperatures.	$1.$ Boiling occurs at a particular temperature when the liquid is heated.
$2.$ Evaporation is a surface phenomenon,i.e.,it takes place only from the surface of the liquid.	$2.$ Boiling is a bulk phenomenon,i.e.,it involves the formation of vapours from the entire liquid.
$3.$ Evaporation causes a cooling effect.	$3.$ Boiling does not cause any cooling effect.

(D) $(i)$ Carbon dioxide is classified as a gas due to the following reasons:
$(a)$ It lacks both a fixed volume and a fixed shape,as it completely fills the container in which it is stored.
$(b)$ It exerts pressure on the walls of the container due to the high kinetic energy and collisions of its particles.
$(ii)$ In gases,the intermolecular distances are very large,and the intermolecular forces of attraction are extremely weak. Because of this,gas particles are free to move randomly in the entire space available to them. Consequently,a gas fills the vessel completely.
$(iii)$ The intermolecular space is maximum in gases,intermediate in liquids,and minimum in solids. When pressure is applied to a gas,the particles move closer together,significantly reducing the volume,which makes gases highly compressible. In contrast,the particles in solids and liquids are already closely packed,leaving very little space for further compression,making them almost incompressible.

(A) Diffusion is the movement of particles from a region of higher concentration to a region of lower concentration.
In $Gases$,the particles are far apart and have high kinetic energy,allowing them to move freely and rapidly in all directions.
In $Liquids$,particles are closer together than in gases,and in $Solids$,they are tightly packed with very little movement.
Therefore,due to high kinetic energy and large intermolecular spaces,the rate of diffusion is highest in $Gases$.

(B) Evaporation is a process in which liquid changes into vapor at any temperature below its boiling point.
This process occurs only at the surface of the liquid because the particles at the surface have higher kinetic energy than the particles in the bulk of the liquid,allowing them to overcome the forces of attraction and escape into the atmosphere.
Therefore,evaporation is considered a surface phenomenon.

(C) Evaporation is a surface phenomenon where particles at the surface of a liquid gain enough kinetic energy to overcome the forces of attraction and escape into the vapor state.
To overcome these intermolecular forces of attraction,the particles require energy.
This energy is taken from the surroundings or the liquid itself,which leads to a cooling effect.
Therefore,heat is absorbed during the process of evaporation.

(D) Boiling is a process in which a liquid changes into a gas at a constant temperature called the boiling point.
Unlike evaporation,which occurs only at the surface of a liquid,boiling occurs throughout the entire volume of the liquid.
Therefore,heat is supplied to the entire mass of the liquid,and bubbles of vapor form within the bulk of the liquid and rise to the surface.
Thus,boiling is considered a bulk phenomenon.

(D) The stability of a state of matter depends on the kinetic energy of its particles.
At higher temperatures,particles have high kinetic energy,leading to a gaseous state.
As the temperature decreases,the kinetic energy of the particles decreases,causing them to come closer together and form a liquid,and eventually a solid.
However,at extremely low temperatures (near absolute zero),the Bose-Einstein Condensate $(BEC)$ state is formed,which is a state of matter characterized by extremely low energy and high stability in quantum terms.
Among the standard states,solid is the most stable at low temperatures,but $BEC$ is specifically defined by its existence and stability at temperatures near absolute zero.

(B) Gases can be liquefied by applying high pressure and reducing the temperature.
Increasing the pressure brings the gas particles closer together,while decreasing the temperature reduces their kinetic energy,allowing intermolecular forces to hold the particles together in a liquid state.

(C) Intermolecular forces of attraction are the forces that hold particles (atoms, molecules, or ions) together in a substance.
In $Solids$, these forces are very strong, keeping particles in a fixed position.
In $Liquids$, these forces are weaker than in solids, allowing particles to move past each other.
In $Gases$, the particles are far apart and move randomly at high speeds, meaning the intermolecular forces of attraction are negligible or least effective.
$Plasma$ consists of ionized gas particles, where the high kinetic energy further overcomes attractive forces.
Therefore, the correct answer is $Gases$.

(D) Evaporation is a surface phenomenon where liquid molecules at the surface gain enough kinetic energy to overcome the intermolecular forces and escape into the vapor phase.
Unlike boiling,which occurs at a specific boiling point throughout the bulk of the liquid,evaporation can occur at any temperature.
As the temperature increases,the rate of evaporation increases because more molecules possess sufficient kinetic energy to escape the surface.

(A) The process of water turning into ice is known as freezing or solidification. During this phase change,water molecules lose kinetic energy and transition from a liquid state to a solid state. According to the principles of thermodynamics,when a substance changes from a higher energy state (liquid) to a lower energy state (solid),it must release energy to the surroundings. Therefore,heat is evolved (released) during the solidification of water into ice.

(B) The boiling point of a liquid is defined as the fixed temperature at which the vapor pressure of the liquid becomes equal to the atmospheric pressure.
Under normal atmospheric pressure $(1 \text{ atm})$,every pure liquid boils at a specific,constant temperature known as its boiling point.
Therefore,boiling occurs at a fixed temperature under normal atmospheric pressure.

(C) The force of attraction between particles is strongest in solids, intermediate in liquids, and weakest in gases.
In the given options, we need to arrange them in increasing order (Gas < Liquid < Solid).
For option $C$: Oxygen is a gas, water is a liquid, and sugar is a solid.
Therefore, the increasing order of forces of attraction is: $\text{Oxygen} < \text{Water} < \text{Sugar}$.

(D) Evaporation is a surface phenomenon where liquid molecules gain enough kinetic energy to escape into the vapor phase.
Factors that increase the rate of evaporation include:
$1$. Increase in surface area: More molecules are exposed to the surface.
$2$. Increase in temperature: Molecules gain higher kinetic energy,allowing more to escape.
$3$. Decrease in humidity: The air can hold more water vapor.
$4$. Increase in wind speed: Water vapor particles are moved away,creating space for more evaporation.
Therefore,an increase in the temperature of water increases the rate of evaporation.

(A) In physics and chemistry,a fluid is defined as a substance that has the ability to flow and does not resist a permanent deformation when subjected to a shear stress.
Both liquids and gases possess the ability to flow,which is why they are collectively referred to as fluids.
Solids,on the other hand,maintain a fixed shape and do not flow under normal conditions.
Therefore,the statement that gases and liquids behave like fluids is correct.

(B) To convert temperature from Celsius $(^{\circ} C)$ to Kelvin $(K)$,we use the formula: $K = ^{\circ} C + 273.15$ (or approximately $273$).
For $25^{\circ} C$: $25 + 273 = 298 \, K$.
For $46^{\circ} C$: $46 + 273 = 319 \, K$.
For $109^{\circ} C$: $109 + 273 = 382 \, K$.
Thus,the correct sequence is $298 \, K, 319 \, K, 382 \, K$.

(C) Sublimation is the process of transition of a substance directly from the solid to the gas phase or from the gas phase directly to the solid phase,without passing through the intermediate liquid state.
Option $A$ is incorrect because the conversion of solid to liquid is called melting or fusion.
Option $B$ is incorrect because the conversion of solid to vapour is called sublimation.
Option $C$ is correct as it describes the deposition process,which is a type of sublimation.
Option $D$ is incorrect because the conversion of vapour to solid is called deposition,not freezing.

(B) The statement is False.
The random,zigzag movement of tiny particles suspended in a fluid (a liquid or a gas) is known as Brownian motion,not the Tyndall effect.
The Tyndall effect refers to the scattering of a beam of light by particles in a colloid or a very fine suspension.

(A) The statement is $True$.
Intermolecular forces are the forces of attraction or repulsion which act between neighboring particles (atoms,molecules,or ions) of matter.
These forces are responsible for the physical state of matter (solid,liquid,or gas) and determine properties like boiling point,melting point,and viscosity.

(TRUE) The statement is $True$.
Solids possess a definite shape and a fixed volume due to strong intermolecular forces of attraction between their constituent particles.
Because of these strong forces,the particles are held in fixed positions and can only vibrate about their mean positions,which prevents them from flowing like liquids or gases.

(TRUE) The statement is True.
Diffusion is the process of movement of particles from a region of higher concentration to a region of lower concentration.
In liquids,the rate of diffusion is influenced by several factors:
$1$. Viscosity: Higher viscosity (thickness) of a liquid creates more resistance to the movement of particles,thereby slowing down the rate of diffusion.
$2$. Chemical Nature: The intermolecular forces and the size of the molecules of the diffusing substances affect how easily they can move through the medium.
Therefore,both viscosity and chemical nature are critical determinants of the diffusion rate in liquids.

(FALSE) The statement is False.
An absolute temperature scale is one that starts at absolute zero $(0 \ K)$,which is the lowest possible temperature where all molecular motion ceases.
The Celsius scale is a relative scale based on the freezing point $(0 \ ^\circ C)$ and boiling point $(100 \ ^\circ C)$ of water at standard atmospheric pressure.
The Kelvin scale is the absolute temperature scale used in science.

(FALSE) The statement is False.
The relationship between the Celsius scale and the Kelvin scale is given by the formula: $T(K) = T(^{\circ}C) + 273.15$.
For $0^{\circ} C$,the temperature in Kelvin is $0 + 273.15 = 273.15 \ K$ (often approximated as $273 \ K$).
Therefore,$0^{\circ} C = 273 \ K$,not $-273 \ K$.

(TRUE) The statement is True.
The relationship between the Celsius scale and the Kelvin scale is given by the formula: $T(K) = T(^{\circ}C) + 273.15$.
For standard calculations,we use the approximation $T(K) = T(^{\circ}C) + 273$.
Substituting $T(^{\circ}C) = -273$,we get $T(K) = -273 + 273 = 0 K$.
Therefore,$-273^{\circ} C$ is equivalent to absolute zero,which is $0 K$.