Unit - 9 Matter

 Unit - 9

Matter

Summary

1. All objects around us are matter.

2. Matter has volume and mass.

3. The amount of matter in any object is called the mass of that object.

4. The space occupied by a substance is called the volume of that substance.

5. There are three states of matter at ordinary temperatures. They are solid, liquid and gas. E

6. Solids have their own shape and definite volume.

7. A liquid has a definite volume but not a definite shape.

8. A gas does not have a definite shape and volume.

9. If the temperature decreases, the state of matter changes.

10. A substance cannot be broken down to form a new substance, such a substance is called a substance.

11. A chemical reaction occurs between two or more elements in a certain ratio

The substance of is called a compound.

12. Mixture of more than 2 or 4 years is called compound.

3. Write answers to the following questions:

  (a) What is substance? Write any two properties of matter.

  (b) What are the three states of matter? An article with a single example.

  (c) Why does ice change into water when heated?

  (d) Write the names of any four principles used in daily life.

  (e) Write the names of any four compounds used in daily life.

  (f) Why does liquid change into gas when heated?

Answer 👉 

(a) A substance is a material with a definite composition. It can be a pure substance or a mixture. Pure substances have a definite chemical composition, while mixtures have variable compositions.

Two properties of matter are mass and volume. Mass is the amount of matter in an object, and volume is the amount of space an object takes up.

(b) The three states of matter are solid, liquid, and gas.

• Solids have a definite shape and volume.
• Liquids have a definite volume, but their shape can change.
• Gases have no definite shape or volume.
• Here is an example of each state of matter:

Solid: ice

Liquid: water

Gas: water vapor

(c) When ice is heated, the molecules move faster and faster. Eventually, they move so fast that they break free from the bonds that hold them together and the ice melts into water.

(d) Four principles used in daily life are the law of conservation of mass, the law of conservation of energy, the law of inertia, and the law of acceleration.

• The law of conservation of mass states that mass cannot be created or destroyed.
• The law of conservation of energy states that energy cannot be created or destroyed, but it can be converted from one form to another.
• The law of inertia states that an object at rest tends to stay at rest, and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
• The law of acceleration states that the acceleration of an object is directly proportional to the net force acting on the object and inversely proportional to the mass of the object.
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(e) Four compounds used in daily life are water, salt, sugar, and carbon dioxide.

• Water is a compound of hydrogen and oxygen. It is essential for life.
• Salt is a compound of sodium and chlorine. It is used to flavor food and to preserve food.
• Sugar is a compound of carbon, hydrogen, and oxygen. It is a source of energy.
• Carbon dioxide is a compound of carbon and oxygen. It is used to make soda and to put out fires.
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(f) When a liquid is heated, the molecules move faster and faster. Eventually, they move so fast that they escape from the liquid and become a gas.

4. Define the following words:

  (a) Compound

A compound is a substance that is made up of two or more elements chemically combined.

(b) Mixture 

A mixture is a substance that is made up of two or more substances that are not chemically combined.

(c) Compound

A compound is a pure substance, while a mixture is not a pure substance.

(d) Evaporation 

Evaporation is the process of a liquid changing into a gas. Volatilization is the process of a solid changing into a gas.

(e) Volatilization 

 Volatilization Melting is the process of a solid changing into a liquid.

5. Distinguish between:

  (a) Solids and liquids

  (b) Elements and Compounds

  (c) Compounds and mixtures

  (d) Evaporation and sublimation

Answer 👉 

(a) Solids have a definite shape and volume, while liquids have a definite volume but their shape can change.

(b) Elements are substances that cannot be broken down into simpler substances by chemical means, while compounds are substances that are made up of two or more elements chemically combined.

(c) Compounds are pure substances, while mixtures are not pure substances.

(d) Evaporation is the process of a liquid changing into a gas, while sublimation is the process of a solid changing directly into a gas without going through the liquid state.