🌈🔥Short Answer-Questions
Q1. What is KMT? Give its main postulates with respect to three states of matter. Or How kinetic molecular theory differentiates states of matter?Q2. Define Boiling Point, Melting Point, Freezing Point, fusion, absolute zero
Q3. What is the difference between evaporation and boiling? What is boiling point? How liquid is converted to gas?
Q4. What is diffusion? Why gases diffuse rapidly, Explain? State Graham’s law of diffusion of gases. Which gas from among CO₂, CH₄ and H₂ will diffuse the fastest and why? Give the reason
Q5. Why density of gases increases on cooling?
Q6.Explain that Effusion depends on mean free path.
Q7. Which variables are kept constant in Boyle's law?
Q8. When a gas is allowed to expand, what will be the effect on its temperature?
Q9. What is pressure? Give its reason and unit.
Q10. Can you reduce temperature of a gas by increasing its volume?
Q11.Explain how evaporation caused a cooling effect?
Q12. What is density, how the density of liquid is affected by temperature and pressure?
Q13. What is Effusion, explain with the examples?
Q14. Discuss the property of evaporation in liquids? Which factors affects the evaporation process?
Q15. Why increase in temperature causes increase in the process of evaporation?
Q16. Describe the process of diffusion in liquids? Why rate of diffusion in liquids is less than gases? Prove with the help of examples. State the factors which influence it?
Q17. Define the allotropy with examples?
🌈🔥Long Answer-Questions
Q1. Define vapour pressure and justify that it is visible in a close system only? How equilibrium state involved in vapour pressure of liquids in close system?
Q2. How boiling point is affected by different factors? How boiling point of a substance is affected by atmospheric pressure?
Q3. Describe the Boyle's law with example?
Q4. Define and explain the Charles' law of gases
Q5. Differentiate between amorphous and Crystalline Solids?
Q6. Explain plasma with the daily life examples?
Q7.Justify that atoms of Bose Einstein condensate are super unexcited and super cooled?
🌈🔥Numericals
🌈🔥Answers of Short Questions
Q1. What is KMT? Give its main postulates with respect to three states of matter. Or How kinetic molecular theory differentiates states of matter?
Answer
Definition
Boltzmann, Maxwell, Kelvin put forward kinetic molecular theory.
Kinetic molecular theory is a hypothetical but practical model which explains the general structures, composition and properties of all the three states of matter.
According to K.M.T, all matter is composed of extremely tiny particles called molecules which are always in a state of continuous random motion possessing kinetic energy. The three states of matter depend upon the arrangements, motions and forces of attraction between these particles.
Postulate of Kinetic Molecular Theory for GASEOUS State
1. The molecular are widely separated from each other.
2. The molecules have negligible volume.
3. The gas molecules are in constant random motion
4. The gas molecules move in straight line until they collide with each other or wall of container
5. The collisions of gas molecular are elastic in nature as during collision molecules do not lose energy
6. Pressure produced when molecules collide with the wall of container
7. There are attractive and repulsive forces been molecules.
Postulate of Kinetic Molecular Theory for Liquid State
According to their kinetic molecular theory liquid state shows following characteristics.
1. The molecules of a liquid are randomly arranged like gases.
2. The molecules of liquids have less kinetic energy than gases.
3. The molecules of liquids are fairly free to move.
4. The Liquids has no definite shape but assumes the shape of container.
5. The Boiling point of liquids depends on the external atmospheric pressure.
6. The Liquids are denser and not compressible like gasses.
Comparison of Three States of Matter according to KMT
Q2. Define Boiling Point, Melting Point, Freezing Point, fusion, absolute zero
Answer
Boiling Point
The temperature at which vapour pressure of a liquid become equal to atmospheric pressure is called boiling point of the liquid.
Freezing Point
The temperature at which the vapour pressure of a liquid state becomes equal to the vapour pressure of its solid state is known as Freezing Point of a liquid. At this temperature liquid and solid coexist in dynamic equilibrium.
Melting or Fusion
The process of state change from solid to liquid upon heating is called Melting or Fusion which is the characteristic of solids. e.g. change (melting) of ice to water
Melting Point
The temperature at which a solid starts melting on heating at which both liquid and solid phases co-exist at equilibrium is called melting point (m.p.). Melting point is the criteria of purity of solid as a pure solid has a sharp and fixed melting point.
Absolute zero
It is the temperature at which an ideal gas would have zero volume. It is equal to –273°C..
Q3. What is the difference between evaporation and boiling? What is boiling point? How liquid is converted to gas?
Answer
How liquid is converted to gas?
When a liquid changes to gas, the particles absorb heat energy and they start vibrating faster and distance between them increases. On constant vibration, intermolecular forces decrease and particles start moving away from each other and change to gas.
Q4. What is diffusion? Why gases diffuse rapidly, Explain? State Graham’s law of diffusion of gases. Which gas from among CO2, CH4 and H2 will diffuse the fastest and why? Give the reason
Answer
Diffusion
The spontaneous mixing of molecules by random motion and collision to form a homogenous mixture is called diffusion. Diffusion is movement of particles from an area of high concentration to one of low concentration. Diffusion results in the gradual mixing of materials, and eventually it forms a homogeneous mixture.
Reason of Rapid diffusion in gases
Gases are rapidly diffusible due to free movement of molecules.
Graham’s law of diffusion of gases
The quantitative relationship between the rate of diffusion of different gases and their molar masses or densities is called Graham’s Law of Diffusion established by a Scottish chemist, Thomas Graham in 1846. This law states that:
“The rate of diffusion of a gas is inversely proportional to the square root of its density or molar mass (under the same conditions of temperature and pressure).”
Reason of
diffusion
According to Graham’s law, gases with
lower molar mass diffuse faster.
Since H₂ has the least molar mass, it
diffuses fastest; CO₂ has the highest, so it diffuses slowest; and CH₄ is
intermediate.
Order of diffusion: CO₂ (44 amu) < CH₄ (16 amu) < H₂ (2 amu)
Q5. Why density of gases increases on cooling?
Answer
The density of gases can be increased by cooling as density of gases is inversely proportional to temperature. Greater the temperature, less will be density of gas and vice-versa.
Q6. Explain that Effusion depends on mean free path.
Answer
The Effusion is escaping of gas molecules through a tiny hole into a space with lesser pressure. For process of effusion, the diameter of hole must be smaller than the molecule's mean free path. (Mean free path is the average distance that a gas particle travels between successive collisions with other gas particles).
Q7. Which variables are kept constant in Boyle's law?
Answer
While studying Boyle’s law, temperature and number of moles of a gas are kept constant.
Q8. When a gas is allowed to expand, what will be the effect on its temperature?
Answer
According to Charle’s law, volume of gas is directly proportional to absolute temperature. When a gas is allowed to expand its volume increases which in turn increases its temperature.
Q9. What is pressure? Give its reason and unit.
Answer
Definition of Pressure
Gas Pressure is the force exerted by gaseous molecules per unit area.
Reason of Pressure
Pressure of a gas is due to the elastic collisions of its molecules with the walls of container.
Pressure (P) = Force (F)/Area (A)
Unit of Pressure
The S.I. unit of pressure is N–m⁻² which is also known as ‘pascal’ abbreviated as ‘Pa’ (which is defined as the pressure exerted by a force of one newton acting on area of one square meter) i.e. 1 Pa is equal to 1N–m⁻²
Pressure (P) = Force (F)/Area (A) = N/m² = 1 Nm⁻² = 1Pa (pascal)
Q10. Can you reduce temperature of a gas by increasing its volume?
Answer
Yes. When the gas expands against an external pressure, the gas transfers some energy to the surroundings. and decreases its temperature.
Q11. Explain how evaporation caused a cooling effect?
Answer
The evaporation is also considered as cooling process because when high kinetic energy molecules escape in the air in the form of vapour. The temperature of remaining molecules falls down. To compensate this deficiency of energy molecules absorb energy from the surrounding, due to which temperature of surrounding decreases and feel cold
Q12. What is density, how the density of liquid is affected by temperature and pressure?
Answer
The density of liquid is defined as mass per unit volume.
D = M/V
Factors affecting Density
Temperature
Liquids are less affected by the temperature. By increasing temperature liquids increased their volume which decreases density.
Pressure
Liquids are slightly affected by pressure. Increase in pressure on liquids increases the density but liquids are not readily compressed due to this density change is negligible.
Q13. What is Effusion, explain with the examples?
Answer
Definition
The Effusion is escaping of gas molecules through a tiny hole into a space with lesser pressure.
Effusion depends upon molecular masses of gases. Lighter gases effuse rapidly than heavier gases.
Q14. Discuss the property of evaporation in liquids? Which factors affects the evaporation process?
Answer
Definition
The process by which a liquid changes to a gas phase is called evaporation. Evaporation is endothermic change in which heat is absorbed.
For example
Clothes dry under the sun due to evaporation in this process water is converted from liquid state into vapours by acquiring from
Reason of Evaporation
Liquid molecules move constantly and collide; most have average kinetic energy, while a few with higher energy overcome attractions and escape as evaporation.
Evaporation is a cooling process
Evaporation cools because high-energy molecules escape, lowering the temperature of the remaining liquid; surrounding energy is absorbed, making it feel cold.
Factors Affecting Evaporation
Q15.Why increase in temperature causes increase in the process of evaporation?
Answer
The rate of evaporation increases with the increase in temperature. Because temperature increases the kinetic molecular energy which overcome the intermolecular forces and makes evaporation rapidly.
For example clothes dry quickly in a sunny day than a cloudy day.
Q16. Describe the process of diffusion in liquids? Why rate of diffusion in liquids is less than gases? Prove with the help of examples. State the factors which influence it?
Answer
Definition: Spreading of liquid molecules throughout the vessel.
Movement: Liquid molecules move from high concentration → low concentration forming a homogeneous mixture.
Rate: Slower than gases due to stronger intermolecular forces and clustered molecules.
Example: A drop of dye or ink spreading in water.
Factors affecting Diffusion
Intermolecular Forces: Weaker forces → faster diffusion; liquids diffuse faster than solids but slower than gases.
Molecule Size: Smaller molecules diffuse faster than larger ones (e.g., alcohol diffuses faster than water).
Molecule Shape: Regular-shaped molecules diffuse faster than irregular-shaped ones.
Temperature: Higher temperature → higher kinetic energy → faster diffusion.
Q17. Define the allotropy with examples?
Answer
Definition
The existence of an element in more than one crystalline forms is known as allotropy. These forms of the element are called allotropes or allotropic forms.
Reason of Allotropy
This happens when the atoms of the element are bonded together in a different way. Different bonding arrangements between atoms result in different structures with different chemical and physical properties.
Examples
Only some elements like sulphur, phosphorus, carbon and tin are elements which show allotropy.
Allotropes of carbon:
🔥Diamond: Carbon atoms in a 4-cornered lattice; very hard.
🔥Graphite: Carbon atoms in hexagonal sheets; slippery and conducts electricity.
🔥Graphene: Single sheet of graphite; extremely strong and conductive.
🔥Fullerenes: Carbon atoms in spheres, cylinders, or egg-shaped structures; unique molecular shapes.
Long Answer-Questions
Q1. Define vapour pressure and justify that it is visible in a close system only? How equilibrium state involved in vapour pressure of liquids in close system?
Answer
Definition
The pressure exerted by vapours in equilibrium with its pure liquid at a particular temperature is called Vapour Pressure.
The equilibrium is a state when rate of evaporation is equal to rate of condensation but in opposite directions.
Explanation or Origin of Vapour Pressure
Vapour pressure takes place in a closed system because in open system or open surface liquid molecule evaporates and mix-up with air.
Unit
The unit of pressure is expressed in mm of Hg, atmosphere, torr or newton per meter square.
Factors Affecting Vapour Pressure
Q3. Describe the Boyle's law with example?
Answer
Boyle's Law/ Pressure-Volume Law
Statement
A characteristic property of gases is their great compressibility. The relationship between pressure and volume of gases is known as Boyle’s law given by Robert Boyle In 1662.
Providing temperature constant, the volume of a fixed mass of a gas is inversely proportional to its pressure. OR The product of pressure and volume of a given mass of a gas at constant temperature is always constant.
Mathematical Expression of Boyle’s Law
V a 1/P (Temperature constant)
V = K x 1/P (Removing proportionality sign (a) by introducing a constant)
PV = K (Constant )
Here K = Constant of proportionality whose value depends upon the amount of the gas, temperature of the gas and the units in which p and V are expressed.]
If, pressure is changed from P1 to P2, the volume will change from V1 to V2, then according to Boyle’s law:
P1V1 = K ––––––––– (1), And
P2V2 = K –––––––––– (2) [Comparing equation (1) and (2).]
P1V1 = P2V2 = K [This is the second form of Boyle’s law]
Where
P1 = initial pressure,
P2 = final pressure,
V1 = initial volume,
V2 = final volume
Experimental Verification
The relationship between volume and pressure at constant temperature is shown in the following figure. Where given mass of a gas at constant temperature shows increase in volume by decrease in pressure. While increase in pressure decreases volume. But in both cases, the product of pressure and volume is constant.
Q4. Define and explain the Charles' law of gases
Answer
Charle’s Law (Effect of Absolute Temperature on Gas Volume)
Statement
In 1787, French physicist Jacques Charles proposed his law to explain the relationship between volume and temperature keeping the pressure constant.
The volume of a fixed mass of a gas held at constant pressure is directly proportional to the absolute (kelvin) temperature. In other words, the ratio of volume of a fixed mass (mole) gas to its absolute temperature at constant pressure always remains constant.
Mathematical Expression
Then, Charles law can be expressed as:
V α T (Pressure constant)
V = KT (Removing proportionality sign by introducing a constant)
V/T = Constant = K [Here K = Constant of proportionality]
If V1 and V2 are the original and changed volume; T1 and T2 are the original and changed temperature, then
V1/T1 = K ---------------------- (1) And
V2/T2 = K ---------------------- (2)
(Comparing equation (1) and (2), we get the second form of Charle’s law)
V1/T1 = V2/T2 = K
Absolute Temperature Scale
Lord Kelvin introduced absolute temperature scale or Kelvin scale. It starts from zero, 0K which is equal to –273°C. It is the temperature at which an ideal gas would have zero volume and known as absolute zero. As Celsius and kelvin scales have equal degree range therefore when zero kelvin is equal to -273°C, and 273 kelvin is equal to zero °C.
Conversion of kelvin temperature and Celsius temperature are vice versa as follows:
K = °C + 273 And °C = K – 273
Experimental Verification
According to Charele’s law if absolute temperature of a gas is doubled, its volume will also double. For example, that if you double the temperature from 300 K to 600 K, at constant pressure, the volume of a fixed mass of the gas will become double
Q6. Differentiate between amorphous and Crystalline Solids?
Answer
Difference between Amorphous and Crystalline Solids
Answer
English scientist William Crookes identify the fourth states of matter known as Plasma.
Plasma are super-hot and super excited atoms. Plasma is distinct state of matter containing a significant number of electrically charged particles which affect its electrical properties and behavior.
It was discovered by adding energy to a gas. As a result some electrons left their atoms and formed positive and negative ions by ionization. In plasma these charged particles react strongly to electric and magnetic fields. If plasma loses heat, the ions will re-form into a gas, emitting the energy which had caused them to ionize.
Some examples of daily life are as follow:
(i) The lightning makes plasma naturally.
(ii) The Artificial (man-made) uses of plasma include fluorescent light bulbs, Neon signs.
(iii) The use of plasma display of television or computer screens.
(iv) The plasma lamps and globes are popular in children's toys and room decoration.
Scientists are experimenting with plasma to make a new kind of nuclear power, called fusion, which will be much better and safer than ordinary nuclear power with less radioactive waste.
Q8. Justify that atoms of Bose Einstein condensate are super unexcited and super cooled?
Answer
The atoms in a Bose-Einstein condensate (BEC) are super unexcited and super cold atoms.
Two scientists Satyendra Bose and Albert Einstein discovered another state of matter in 1920 but they did not have the equipment and facilities to make it happens at that time.
Afterward in 1995 two other scientists Eric Cornell and Carl Weiman also proposed another state of matter known as Bose-Einstein Condensate (BEC)
They discovered that as plasma are super-hot and super excited atoms. The atoms in a Bose-Einstein condensate (BEC) are totally opposite. They are super unexcited and super cold atoms.
Condensation happens when several gas molecules come together and form a liquid. It all happens because of a loss of energy. Gases are really excited or energetic atoms. When they lose energy, they slow down and begin to gather. They can gather into one drop.
For example, when you boil water. Water vapour in the form of steam condenses on the lid of pot. Vapour cool and become a liquid again. You would then have a condensate. (Absolute Zero is a temperature where all the atomic activities stop theoretically).
The BEC happens at super low temperatures. When we get a temperature near absolute zero, all molecular motion stops due to depletion of energy, and atoms begin to clump.
The result of this clumping is the BEC. In common we cannot see this state in observable nature, because it is very difficult to reach at very low temperature under normal lab conditions.
🔥💨 Gases, Liquids & Solids MCQs | Ace Matter Concepts with Inamjazbi Learn Chemistry! 🧪✨
Q: Pick the correct answer (MCQs)
1️⃣ Which of the following gas diffuses fastest?
🟨 A Hydrogen
🟩 B Chlorine
🟦 C Fluorine
🟪 D Helium
2️⃣ The vapour pressure of a liquid increases with the increase of:
🟨 A Pressure
🟩 B Polarity of molecules
🟦 C Intermolecular forces
🟪 D Temperature
3️⃣ The freezing point depends upon:
🟨 A Nature of liquid
🟩 B Pressure
🟦 C Temperature
🟪 D Volume
4️⃣ One atmospheric pressure is equal to:
🟨 A 10325 Pascal
🟩 B 106075 Pascal
🟦 C 10523 Pascal
🟪 D 101325 Pascal
5️⃣ Which of the following does not affect the boiling point?
🟨 A Intermolecular forces
🟩 B Initial temperature of liquid
🟦 C Nature of liquid
🟪 D External pressure
6️⃣ The mobility of liquids is lesser than:
🟨 A Solids
🟩 B Gases
🟦 C Bose Einstein Condensate
🟪 D Plasma
7️⃣ Which of the following have sharp melting point in solids?
🟨 A Plastic
🟩 B Rubber
🟦 C Glass
🟪 D Diamond
8️⃣ Which of the following is lightest form of matter?
🟨 A Solid
🟩 B Liquid
🟦 C Gases
🟪 D Plasma
9️⃣ The liquid molecules leave the surface of liquid in evaporation process because:
🟨 A Energy is low
🟩 B Energy is moderate
🟦 C Energy is high
🟪 D None of these
🔟 The density of gases increases when its:
🟨 A Pressure increased
🟩 B Temperature increased
🟦 C Volume increased
🟪 D None of these
1️⃣1️⃣ ………….. is the escape of molecules from the surface of liquid.
🟨 A Evaporation
🟩 B Melting
🟦 C Boiling
🟪 D Freezing
1️⃣2️⃣ The ……… is the intermediate state between solid and gas.
🟨 A Gas
🟩 B Liquid
🟦 C Solid
🟪 D Plasma
1️⃣3️⃣ The number of common states of matter is:
🟨 A 1
🟩 B 3
🟦 C 5
🟪 D 4
1️⃣4️⃣ Neither definite shape nor volume is the property of:
🟨 A Gas
🟩 B Liquid
🟦 C Solid
🟪 D Plasma
1️⃣5️⃣ All types of matter are composed of smallest particles which are always ………...
🟨 A Stationary
🟩 B In motion
🟦 C At rest
🟪 D None of them
1️⃣6️⃣ Gas possesses neither definite shape nor definite ………..
🟨 A Mass
🟩 B Volume
🟦 C Density
🟪 D None of them
1️⃣7️⃣ The temperature at which liquid starts boiling is called ……… point.
🟨 A Boiling point
🟩 B Melting point
🟦 C Freezing point
🟪 D None of them
1️⃣8️⃣ It is the temperature at which the vapour pressure of a liquid becomes equal to its external pressure.
🟨 A Triple point
🟩 B Freezing point
🟦 C Boiling point
🟪 D None of them
1️⃣9️⃣ The state of matter in which molecules are tightly packed and possess only vibrational motion is:
🟨 A Plasma
🟩 B Liquid state
🟦 C Solid state
🟪 D Gaseous state
2️⃣0️⃣ The process in which solid directly changes to gas is called:
🟨 A Boiling
🟩 B Melting
🟦 C Sublimation
🟪 D Evaporation
2️⃣1️⃣ If a gas jar of colourless air is placed over a gas jar of brownish coloured NO₂ gas and gases are allowed to interact freely, the uniform colour developed in both jars after some time will be result of:
🟨 A Evaporation
🟩 B Diffusion
🟦 C Sublimation
🟪 D Effusion
2️⃣2️⃣ If two gases at room temperature are allowed to diffuse through a porous membrane into a chamber at reduced pressure, the gas that diffuses at the slowest rate will have:
🟨 A Highest molecular mass
🟩 B Highest density
🟦 C Least density
🟪 D Both B and C
2️⃣3️⃣ Which gas will diffuse at the highest rate?
🟨 A Cl₂
🟩 B F₂
🟦 C CO
🟪 D NH₃
2️⃣4️⃣ The two gases which have the same molecular mass will have:
🟨 A Same boiling point
🟩 B Same diffusion rate
🟦 C Same effusion rate
🟪 D Both B and C
2️⃣5️⃣ Which of the following pairs of gases will diffuse at the same rate?
🟨 A CO and N₂
🟩 B CH₄ and NH₃
🟦 C CO₂ and NO₂
🟪 D CO₂ and O₂
2️⃣6️⃣ Which one has the rate of diffusion in ascending order?
🟨 A NH₃ and CH₄
🟩 B H₂, O₂
🟦 C N₂, O₂
🟪 D CH₄, CO₂
2️⃣7️⃣ Which of the following is the correct order of rate of diffusion?
🟨 A Solid > Liquid > Gas
🟩 B Gas > Liquid > Solid
🟦 C Liquid > Gas > Solid
🟪 D Gas > Solid > Liquid
2️⃣8️⃣ Which theory deals with the properties governed by the arrangement of particles?
🟨 A Bohr’s theory
🟩 B Arrhenius theory
🟦 C Kinetic theory
🟪 D Dalton’s theory
2️⃣9️⃣ The kinetic theory is so named because it deals with:
🟨 A Particles motion
🟩 B Rate of diffusion
🟦 C Particles density
🟪 D Particles volume
✅ Answers with Short Reason:
1️⃣ 🟨 Hydrogen – Lightest gas diffuses fastest
2️⃣ 🟪 Temperature – Vapour pressure rises with temperature
3️⃣ 🟨 Nature of liquid – Freezing point depends on substance
4️⃣ 🟪 101325 Pascal – Standard atmospheric pressure
5️⃣ 🟩 Initial temperature of liquid – Does not affect boiling point
6️⃣ 🟩 Gases – Liquids are less mobile than gases
7️⃣ 🟪 Diamond – Crystalline solids have sharp melting points
8️⃣ 🟦 Gases – Lightest form of matter
9️⃣ 🟦 Energy is high – Molecules with high energy escape surface
🔟 🟨 Pressure increased – Density rises with pressure
1️⃣1️⃣ 🟨 Evaporation – Molecules escape from surface of liquid
1️⃣2️⃣ 🟩 Liquid – Intermediate state between solid & gas
1️⃣3️⃣ 🟩 3 – Three common states of matter: solid, liquid, gas
1️⃣4️⃣ 🟨 Gas – Neither definite shape nor volume
1️⃣5️⃣ 🟩 In motion – All matter composed of moving particles
1️⃣6️⃣ 🟩 Volume – Gas has no definite volume
1️⃣7️⃣ 🟨 Boiling point – Temp when liquid starts boiling
1️⃣8️⃣ 🟦 Boiling point – Vapour pressure = external pressure
1️⃣9️⃣ 🟦 Solid state – Molecules tightly packed, only vibrate
2️⃣0️⃣ 🟦 Sublimation – Solid directly changes to gas
2️⃣1️⃣ 🟩 Diffusion – Gases mix due to molecular motion
2️⃣2️⃣ 🟪 Both B & C – Slowest gas has high density & mass
2️⃣3️⃣ 🟪 NH₃ – Lightest among options, diffuses fastest
2️⃣4️⃣ 🟪 Both B & C – Same mass → same diffusion/effusion
2️⃣5️⃣ 🟨 CO & N₂ – Same molecular mass → same rate
2️⃣6️⃣ 🟩 H₂, O₂ – Ascending diffusion rate: H₂ < O₂
2️⃣7️⃣ 🟩 Gas > Liquid > Solid – Fastest diffusion in gases
2️⃣8️⃣ 🟦 Kinetic theory – Explains matter properties via particle motion
2️⃣9️⃣ 🟨 Particles motion – Theory focuses on motion of particles