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The force of attraction between the molecules of similar kind is called force of cohesion. 

Example: The forces between water molecules. This force of cohesion keep the molecules of the substance bind together. The force of attraction between different types of molecules is called force of adhesion. 

Example: When a glass filled with water is emptied some water I particles remain stuck to the glass due to the adhesion between water molecules and glass.

The correct answer is:

gases

(a) Evaporation takes place at all temperature.

(b) Freezing process is just reverse of melting.

(c) Sublimation is a process that involves direct conversion of a solid into its vapor on heating.

(d) The temperature at which a solid converts into a liquid is called its melting point.

(e) The smallest unit of matter that exists freely in nature is called molecule.

(f) Molecules of a substance are always in a state of motion and so they possess kinetic energy.

(g) Intermolecular space is maximum in gases less in liquids and the least in solids.

(h) Intermolecular force of attraction is maximum in solids, less in liquids and the least in gases.

A substance which can change its state

(b) oxygen

Intermolecular force of attraction — The force of attraction between the molecules (like molecules or unlike molecules) is called intermolecular force of attraction.

The correct answer is:

liquids

The correct answer is:

boiling point

(a) Formation of water vapour from water is vaporisation. 

(b) Disappearance of camphor is sublimation. 

(c) Conversion of ice into water is melting. 

(d) Conversion of water into steam is boiling.

(a) Formation of water vapour from water is vaporation.

(b) Disappearance of camphor is sublimation.

(e) Conversion of ice into water is melting.

(d) Conversion of water into steam is boiling.

(a) Formation of water vapor from water is evaporation.

(b) Disappearance of camphor is sublimation.

(c) Conversion of ice into water is melting.

(d) Conversion of water into steam is boiling.

(a) Naphthalene, camphor, dry ice.

(b) Paper, sugar.

(c) Glass, stone, pen.

(a) Naphthalene, camphor, dry ice. 

(b) Oxygen, hydrogen, nitrogen 

(c) Glass, stone, pen.

MELTING POINT:

The temperature at which a solid starts changing into LIQUID without further increase in temperature is called MELTING POINT.” 

Or 

The constant temperature at which solid changes into liquid.”

Example : Ice (solid) melts at Q?C into water (liquid) when heated.

BOILING POINT: “The temperature at which a LIQUID start changing in vapor without a further rise in temperature.

Or

‘The constant temperature at which a LIQUID starts changing into GAS (vapors)

Example: Boiling point of water (liquid) is 100°C.

True The melting point of ice is 0°C.

False Boiling takes place at all temperatures.

Mass of the solute = 20g

Volume of the solution = 800ml

Mass by volume % = \(\frac{Mass\,of\, the\, solute}{Volume\,of\,the\, solution}\times100= \frac{20}{800}\times\,100 = 2.5 %\)%

EVAPORATION: “The change of state of a liquid to vapor at all temperatures from the surface of the liquid is called evaporation.”

Molecules are the smallest unit of matter. They exhibit all the properties of that kind of matter and is capable of independent existence.

The smallest particle from which matter is made up is atom.

There are large intermolecular gaps in 

 (d) air

INTER-MOLECULAR FORCES OF ATTRACTION: “The forces of attraction between the molecules of the matter is called the inter-molecular force of attraction.”

This intermolecular force is maximum in solids, less in liquids and least in gases.

3. weaker than in solids

1. B 

2. A 

3. D 

4. C

a) Fig ‘a’ is a pure substance. Because particles are evenly distributed. 

b) Fig ‘b’ is a mixture. Because particles are unevenly distributed.

(a) All the molecules of a substance are identical.

(b) The inter-molecular spacing is least in solids more in liquids and still more in gases.

(c) The molecular motion in liquid and gas is in zig-zag path.

(d) In a solid, the molecules vibrate to and fro but they remain at their fixed positions.

(e) The inter-molecular forces are the weakest in gases.

(f) A solid exerts pressure downwards on its base.

(g) The gases are least dense.

(h) A solid is most rigid.

Chromatography : 

Chromatography is a laboratory technique for the separation of mixtures into its individual components. 

Uses:

1.  Used to separate components of ink and dyes. 
2.  Used to separate the coloured pigments in plants. 
3.  Used to determine the chemical composition of many substances. 
4.  Used in crime scene investigations. 
5.  Used in hospitals to detect alcohol levels in a patient’s blood stream. 
6.  Used by environmental agencies to detect the level of pollutants in water supplies. 
7.  Used by pharmacists to determine the amount of each chemical found in each product.

1. Ice cream is made by churning a mixture of milk, sugar and flavours.

2. This mixture is slowly chilled to form ice cream. 

3. The churning process disperses air bubbles into the mixture by foaming and break up the large ice crystals into tiny particles. 

4. The result is a complex substance which contains solids, liquids and gases. 

5. This is the ice cream. 

6. Ice cream is a colloid.

Substances that can flow are called fluids. e.g. gases (oxygen, hydrogen), liquids (water, petrol, sulphuric acid).

1. they can flow

1. The reason for this property of gases is that there is very large intermolecular space between gas molecules. On mere applying pressure, they are easily compressed.

2.In liquids intermolecular force is weaker than that of solids. So molecules in a liquids can slip over one another and liquids can flow uniike solids.

3 .We need to classify things in order to distinguish them. In this way, things can be categorized and can be easily studied. 

4. Pure substances consists of only one kind of matter. All the particles of a pure substance are alike. It has a definite composition and similar properties. This is the reason that pure substances have fixed melting or boiling points.

5. Electricity neither has mass nor it occupies space. Beside it can not be seen by our eyes. This is why electricity is not considered mattet.

Gases occupy the entire space of the container.

This is because there is some space between the particles of water in which the salt particles get accommodated when dissolved.

When a gas jar full of bromine vapors (reddish brown) is inverted over a gas jar containing air over it. It is observed that after some time, the reddish brown vapors of bromine also spread out into the upper jar. This mixing is called diffusion. The rate of diffusion is the fastest in gases and the slowest in solids. It increases with an increase in temperature.

The particles of matter have the force acting between them. This force keeps the particles together. The strength of this force of attraction is lesser in chalk, hence it could be broken easily into smaller pieces. 

But the strength of the inter-molecular force of attraction is very strong in coal, therefore it is not possible to break them into small pieces.

Solids:

1. The molecules here are very tightly packed having negligible or veiy less intermolecular space.

2. They have the strongest intermolecular force of attraction.

3. The molecules have very small vibration about their mean position i.e. small amplitude.

4. They have a definite shape and volume.

5. They are generally hard and rigid.

6. They are good conductors of heat.

Liquids: 

1. Molecules are less tightly packed. 

2. The intermolecular force of attraction is less than that of solids. 

3. The molecules here can move from one place to another 

4. Do not have any particular shape of their own and thus acquire the shape of the vessel. 

5. A particular quantity of a liquid has a definite volume at a given temperature. 

Gases : 

1. The force of attraction between the molecules is the least. 

2. The intennolecular space is the largest. 

3. Neither have a definite shape nor a defmite volume. 

4. The molecules move independently. 

5. Worst conductors of heat.

Aim : 

To separate components in the mixture of napthaleine and salt.

 Apparatus: 

China dish, cotton plug, funnel, burner. 

Method : 

Separation mixtures by sublimation. 

Procedure : 

1. Take 4 table spoons of mixture in a China dish.
2.  Take the glass funnel and plug the mouth of the funnel with cotton plug. 
3.  Invert the funnel over the China dish. 
4.  Keep the dish on the stand of stove and heat for some time. 

Observation : 

1.  Vapours of napthaleine solidified on the walls of the funnel. 
2.  Salt remains in the China dish.

1. Wood : Chair 

2. Paper : Book 

3. Plastic : Bucket 

4. Metals : Copper wire 

5. Leather : Shoes 

6. Cloth : Shirt or bag

Living matter: 

1. The earth is home to all kinds of plants and animals. They can grow, move and reproduce on their own. 

2. It is natural only. 

Non-living matter: 

1. Most of the matter in the universe is non-living. It means that it does not grow, move or reproduce on its own. 

2. It can be natural or man made.

The two main types of matter are :

1. Living matter: The earth is home to all kinds of plants and animals. They can grow, move and reproduce on their own. Examples : Plant, lotus, animals, human etc. 

2. Non-living matter : Most of the matter in the universe is non-living. It means that it does not grow, move or reproduce on its own. It can be natural or man made. 

(a) Natural matter: It occurs in nature and can be used to make more useful substances, e.g., wood, coal, silk, water, stone, cotton, jute, cereals, fruits, etc. 

(b) Man-made matter : It is produce artificially from natural matter, e.g., plastics, soaps, detergents, medicines, glass, nylon, steel, ceramic, etc.

(a) False. 

Matter can exist in different states.

(b) True.

If the intermolecular space is more than the intermolecular force will be weaker.

(c) False. 

Gases and liquids can flow.

(d) False. 

Solids cannot be compressed easily.

(e) True 

The smallest part of an element capable of independent existence 4s called an atom.

(f) False. 

The intermolecular space in a gas is very large.

Colloids are heterogeneous mixtures in which the particle size is too small to be seen with the naked eye, but big enough to scatter light.

Ex : Milk, Cheese, Ghee, etc.

Emulsion is a mixture consisting of two liquids that do not mix and settle into layers when they left undisturbed. 

Ex : Mixture of oil and water.