Matter

It’s fascinating how everything around us, from the ground beneath our feet to the air we breathe, is actually made up of tiny particles packed together in different ways! It called as”matter,”

Think about the things you see every day. A sturdy rock on the ground stays the same shape no matter where you put it, right? That’s a solid. Solids have their own definite shape and a specific amount of space they occupy, what we call a fixed volume. The tiny building blocks inside a solid are snuggled up really close to each other, barely moving.

Now imagine pouring water into a glass. That’s because water is a liquid. Liquids have a set amount of volume – a liter of water is always a liter of water – but they don’t have a shape of their own. The tiny particles in a liquid are still quite close together, but they have enough freedom to slide past one another, which allows the liquid to flow and fit its container.

And what about the air? You can’t see it, but it’s definitely there! If you’ve ever blown up a balloon, you know that air will spread out to fill the entire space. Air is a gas, and gases have neither a fixed shape nor a fixed volume. Their tiny particles are much farther apart than in liquids or solids and are constantly zipping around in all directions, filling whatever space they’re in.

What’s really interesting is that we can actually change matter from one of these forms to another simply by heating things up or cooling them down. Think about an ice cube. It’s solid water. If you heat that water even more, it will eventually turn into steam, which is water in its gaseous form. The reverse happens when you cool things down – steam turns back into liquid water, and liquid water freezes into solid ice.

This change in state all comes down to how much energy these tiny particles have. When we heat something, we give those particles more energy, making them move around more and spread out. When we cool something down, we take energy away, causing the particles to slow down and get closer together.

So, in a nutshell, the matter all around us exists in different states – solid, liquid, and gas – depending on how its tiny particles are arranged and how much energy they possess. And by simply adding or removing heat, we can make these states change!

EXERCISE- I

Question 1.
Define matter.
Answer:Matter is anything in the universe that has mass and takes up space (volume). It has a tangible presence – you can touch it, feel it, and it occupies a certain amount of room.

Question 2.

What are the two main types of matter? Give two examples for each type.

Answer: we can generally categorize it into two main types: mixtures and pure substances.

For mixtures, think of things like:

Air: It’s a blend of different gases like nitrogen, oxygen, and others, all mixed together but not chemically bonded.
Saltwater: You’ve got salt (sodium chloride) dissolved in water. Then, we have pure substances, which are consistent throughout. These come in two forms:

Elements: These are the simplest forms of matter and can’t be broken down further by chemical means. Gold (Au) and oxygen gas (O2) are great examples. Gold is just gold atoms, and oxygen gas is made of two oxygen atoms bonded together, but it’s still just oxygen.
Compounds: These are formed when two or more different elements are chemically bonded in a fixed ratio. Water (H2O) and table salt (NaCl) are common examples. Water always has two hydrogen atoms for every one oxygen atom, and table salt always has one sodium atom for every one chlorine atom.

Question 3.

Answer:Living things are built of cells, constantly engage in metabolism, grow and become more complex, can reproduce, respond to their surroundings, show movement, adapt over time, maintain homeostasis, and have a defined lifespan. Non-living things lack these fundamental characteristics.

Differentiate between living and non-living matter.

Question 4.
Select natural and man made matter from the following
list: Wood, plastic, silk, medicines, detergents, coal, water, ceramic, cotton, glass, nylon, fruits.

Answer:Natural Matter: Wood, silk, coal, water, cotton, fruits.

Man-made Matter: Plastic, medicines, detergents, ceramic, glass, nylon.

EXERCISE-II

Question 1.
Name the smallest particle from which matter is made up.
Answer:Atoms.

Question 2.

What are molecules ?

Answer:Molecules are simply groups of two or more atoms stuck together by chemical bonds. Think of them as the tiny LEGO bricks of everything around us. Water, the air, and even sugar are all examples, each with a unique arrangement of atoms that gives it its special characteristics.

Question 3.

Give one difference between atoms and molecules.

Answer:atoms as tiny individual LEGO bricks. When these bricks join together, they form molecules.

Question 4.
Define:
(a) Intermodular force of attraction.
(b) Intermodular space.

Answer:a) Intermolecular force of attraction: This is the pull that exists between separate molecules, making them stick together to some extent.

(b) Intermolecular space: This refers to the empty area or gaps that exist between individual molecules.

Question 5.

Name the three states of matter and define them.

Answer:Solid: Keeps its shape and volume.

Liquid: Keeps the same volume but takes the shape of its container.

Gas: Expands to fill any space.

Question 6.

What are fluids ? Give two examples

Answer:Fluids flow and take the shape of their container because their particles move freely. Think of water, the liquid all around us, and air, the gas we breathe – both are fluids! They don’t hold a rigid shape like solids and easily change when a force acts on them.

Question 7.

Classify the following into solids, liquids and gases.

Oxygen, milk, common salt, wax, stone, L.P.G, carbon- dioxide, sugar, mercury, coal, blood, butter, copper, coconut oil, kerosene.

Answer:Solids: common salt, wax, stone, sugar, coal, butter, copper

Liquids: milk, mercury, blood, coconut oil, kerosene

Gases: Oxygen, L.P.G, carbon-dioxide

Question 8.
Give reasons
(a) Liquids and gases flow but solids do not ?
(b) A gas Alls up the space available to it.
(c) The odour of scent spreads in a room.
(d) We can walk through air.
(e) Liquids have definite volume but no definite shape.
(f) When a teaspoon of sugar is added to half a glass of water and stirred, the water level in the glass remains unchanged.
(g) When an empty gas jar is inverted over a gas jar containing a coloured gas, the gas also spreads into the empty jar.
(h) A red ink drop added to a small amount of water in a glass turns the water red in some time.

Answer:(a) Liquids and gases flow because their particles can slide around, unlike the tightly packed particles in solids.

(b) Gases spread out to fill any space because their particles are always moving freely until they bump into something.

(d) We can walk through air so easily because its particles are really far apart and don’t hold onto each other much.

(e) Liquids keep the same amount, but they’ll take on the shape of whatever you pour them into because their particles can still move past each other.

(f) When sugar dissolves without changing the water level much, it’s because the tiny sugar bits tuck into the gaps between the water bits.

(g) The coloured gas spreading into the empty jar is just its moving particles naturally mixing with the air in the other jar.

(h) That red ink turning the water red is the ink particles and water particles constantly jiggling and spreading out together.

Question 9.
Define:
(a) cohesive force
(b) diffusion
(c) Brownian movement

Answer:(a) Cohesive force: It’s the mutual attraction between identical molecules, the reason water forms those lovely beads.

(b) Diffusion: Think of it as nature’s way of evenly distributing things, like when ink gently spreads in water.

(c) Brownian movement: That jittery dance of tiny particles in a liquid or gas, all thanks to being bumped around by the surrounding molecules.

Question 10.

Why is an egg kicked out of a bottle when air is blown inside the bottle?

Answer:When you blow air into the bottle, you increase the air pressure inside.¹This higher pressure pushes against the egg from the inside with more force than the air pressure outside the bottle, effectively kicking the egg out

EXERCISE-III

Question 1.
State the three effects of heat on matter.
Answer:Heat can make things expand, change their state (like ice melting to water), or even cause chemical changes (like wood burning).

Question 2.
(a) Define : interconversion of states of matter.
(b) What are the two conditions for the interconversion of states of matter ?

Answer:a) Interconversion of states is when a substance goes solid, liquid, or gas to another one. Think melting ice or boiling water.

(b) The two main triggers for these changes are:

Temperature Changes: Heating adds energy, making particles move more and potentially break free (like melting or boiling). Cooling removes energy, slowing particles down and allowing them to get closer together (like freezing or condensation).
Pressure Changes: Squeezing (increasing pressure) or releasing the squeeze (decreasing pressure) can also push particles closer together (gas to liquid or solid) or allow them to spread out more. This is especially noticeable with gases.

Question 3.
Define the following terms:
(a) Fusion
(b) Vaporisation
(c) Condensation
(d) Sublimation
(e) Diffusion
(f) Melting point
(g) Boiling point
(h) Liquefaction

Answer:(a) Fusion (Melting): Solid becomes liquid with heat, like ice to water.

(b) Vaporization (Boiling/Evaporation): Liquid turns into gas or vapor, think boiling water to steam.

(d) Sublimation: Solid goes straight to gas, like dry ice forming mist.

(e) Diffusion: Particles spread out from crowded to less crowded areas, like perfume filling a room.

(f) Melting Point: The exact temperature a solid starts to melt (0°C for ice).

(g) Boiling Point: The exact temperature a liquid rapidly turns to gas (100°C for water at normal pressure).

(h) Liquefaction: Turning a gas into a liquid, often by cooling or squeezing it, like propane in a tank.

Question 4.
Differentiate between:
(a) Solidification and condensation
(b) Melting and boiling
(c) Gas and vapour
(d) Miscible and immiscible liquids.

Answer:(a) Solidification vs. Condensation:

Think water turning to ice (solidification) versus water vapor in the air becoming liquid water like dew (condensation).

(b) Melting vs. Boiling:

Ice becoming water is melting. Water becoming steam is boiling. Solid to liquid, then liquid to gas.

Both are like air, but a vapor (like steam or petrol smell) is easier to turn back into a liquid than a regular gas like the oxygen we breathe.

(d) Miscible vs. Immiscible Liquids:

Liquids that mix perfectly, like water and alcohol, are miscible.

Question 5.

Give reasons :

(a) How is interconversion of states of matter different from chemical reaction ?

(b) Why does a solid not flow, but a liquid flows ?

Answer:(a) Think of it this way: melting ice is like neatly stacked oranges becoming a pile – still oranges, just arranged differently. A chemical reaction is like taking those oranges and turning them into orange juice – something completely new!

(b) Imagine a crowded concert: in a solid, everyone’s stuck shoulder-to-shoulder, just vibrating a little. In a liquid, it’s still crowded, but people can squeeze past each other.

Question 6.

How does a liquid change into its gaseous state? Explain ?

Answer:When a liquid heats up, its tiny parts move faster and break free from each other. Some escape as gas from the surface. If it gets hot enough, the whole liquid bubbles and quickly turns into gas – that’s boiling!

Question 7.

Water cycle is an example of interconversion of states of water. Explain.

Answer:The sun’s warmth drives the continuous water cycle. Liquid water evaporates into invisible vapor , which then cools and condenses into clouds . These clouds release water back to Earth as precipitation , which then collects and the cycle begins anew . This natural process showcases water’s amazing transformations between liquid, gas, and solid states .

Question 8.

What happens to a metal ball when it is heated? What does this show?

Answer: This happens because the heat energy makes the metal atoms vibrate more vigorously. These increased vibrations cause the atoms to move slightly farther apart, resulting in an overall expansion of the metal.

This phenomenon, called thermal expansion, demonstrates that the volume of a solid material changes with temperature. It shows that the particles within a solid are in constant motion, and their kinetic energy increases with heat, leading to an increase in the average distance between them.

Question 9.

Why does a candle become smaller on burning with time?

Answer: This gas combines with air and burns, producing light, heat, and other gases. Since the solid wax is turning into gases that float away, the candle gets smaller as it burns.

OBJECTIVE TYPE QUESTIONS

Question 1.
Fill in the blanks :

(a) Water is a matter because it has mass and occupies space.
(b) Any matter which has a definite volume but no definite shape is called a liquid.
(c) Liquids and gases can flow.
(d) The molecules are at a greater distance in gases compared to liquids.
(e) Water boils at 100 °C.
(f) The physical state of a substance, which has neither fixed volume nor fixed shape is a gas.

Question 2.
Write whether the following statements are true or false.

(a) Only water can exist in three different states.
(b) If the container in which a gas is collected has an opening, the gas will flow out and spread itself indefinitely.
(c) Solids have the large inter-molecular space.
(d) There is no difference between evaporation and boiling.
(e) All solids, on heating, first change to the liquid and then to the gaseous state always.
(f) The intermolecular force of attraction is the weakest in gases.
(g) A gas has no free surface.

Answer:
(a) True
(b) True
(c) False
Correct: Solids have the very small (negligible) inter-molecular space.
(d) False
Correct : There is a difference between evaporation and boiling.
(e) False
Correct : Few solids, on heating, first change to the liquid and then to the gaseous state always.
(f) True
(g) True

Question 3.
For each of the following statements, say whether it describes a solid, a liquid or a gas.

(a) Particles move about very quickly but do not leave the surface : Liquid
(b) Particles are quite close together : Solid
(c) Particles are far apart and move in all directions : Gas

Question 4.
Match the following :

Question 5.
Name the phenomenon which causes the following changes:
(a) Formation of water vapour from water.
(b) Disappearance of camphor when exposed to air.
(c) Conversion of ice into water.
(d) Conversion of water into steam.

Answer:(a) Evaporation

(b) Sublimation

(d) Vaporization

Question 6.
Give two examples for each of the following :
(a) Substances which are sublime.
(b) Substances which do not change their states.
(c) Substances which are rigid and not compressible.

Answer:(a) Substances which sublime:

Dry ice (solid carbon dioxide)
Camphor

(b) Substances which do not change their states (under typical conditions):

Wood (it might burn, but doesn’t typically melt, boil, or sublime at everyday temperatures and pressures)
Glass (similarly, it remains a solid under normal conditions)

Diamond
Steel

MULTIPLE CHOICE QUESTIONS

1. Which one is a kind of matter :
(a) light
(b) petroleum
(c) sound
(d) heat

Answer:(b) petroleum

2. the state of matter which has no definite shape or volume is called
(a) solid
(b) liquid
(c) gas
(d) water

Answer:(c) gas

3. There are large intermolecular gaps in
(a) water
(b) iron ball
(c) common salt ..
(d) air

Answer:(d) air

4. All kinds of matter
(a) occupy space and have a definite mass
(b) have mass and a definite shape
(c) can change their states
(d) have a definite volume

Answer:(a) occupy space and have a definite mass

5. A kind of matter which can sublime is
(a) water
(b) plastic
(c) milk
(d) iodine

Answer:(d) iodine

6. A substance which can change its state
(a) wood
(b) oxygen
(c) paper
(d) cloth

Answer:(b) oxygen

7. The process by which a solid changes into a liquid is called
(a) freezing
(b) melting
(c) condensation
(d) evaporation

Answer:(b) melting