Introduction:

From many physical and chemical evidences we know that matter is composed of small particles called molecules. There are three states of matter. Solids , liquids and gases . These three states of matter are explained on the basis of Kinetic Molecular Model of Matter (KMT) .

Question 1: Using Kinetic molecular theory explain three States of matter.

Kinetic Molecular Model (KMT) :

Kinetic Molecular Model states that ” All matter is composed of small particles called molecules. On the basis of arrangement of molecule and strength of intermolecular forces matter is divided into 3 states. Solids , liquids and gases . Kinetic molecular model of matter explain different properties of these States of matter.

Sub-Question: Using Kinetic molecular theory explain the properties of solids ?

The properties of solids are given by ,

1. Solids are made up of those molecules that are packed closely in a specific pattern in compact form.
2. These molecules vibrate about their mean position.

iii. The intermolecular forces between molecules are very strong.

1. Solids have a specific shape and a specific volume.
2. The melting point of solids is fixed and sharp.
3. The distance between molecules is less than the size of molecules.

Sub-Question: Using Kinetic molecular theory explain the properties of liquids ?

The properties of liquids are given by ,

1. Liquids are also made up of molecules which are close togather.
2. The pattern of molecules unlike solids is not fixed . The molecules in liquids can change their position.

iii. Molecules can change shape so they adopt the shape of container.

1. Liquids have no specific shape and have a specific volume.
2. The attractive forces between molecules of liquids are weaker than that of solids and Stronger than that of gases.
3. The size of molecules is such that the liquids have no empty spaces between molecules.

Sub-Question: Using Kinetic molecular theory explain the properties of gases?

The properties of gases are given by ,

1. A gas is state of matter whose molecules are in constant random motion.
2. The distance between molecules is greater as compared to the size of molecules of gases.

iii. The molecules keep striking the walls of container and each other.

1. The attractive forces between molecules are nearly negligible so they can move about.
2. Gases have no definite shape and no definite volume.

• Fluids:

Liquids and solids doesn’t maintain a specific shape so they have ability to flow . They are collectively known as fluids.

We can define fluid as ‘ An object that has ability to flow is called fluid. ‘ e.g water has ability to flow so water is a fluid.

• Plasma :

There is another state of matter which is usually called the fourth state of matter which is known as Plasma. Plasma contains free electrons and those atoms from which electrons are removed. Plasma exists where the temperature is too high and thermonuclear reactions take place. For example , Sun.

SLO Question:

• Which statement is not true about solids ?

1. Molecules of solids vibrate about their mean position.
2. The intermolecular forces between molecules are strong.
3. They have a definite shape and a definite volume.
4. They have ability to flow.

Answer:

As solids have molecules that are in compact form so they don’t have ability to flow so option d is correct.

• Which statement is not true about liquids?

1. Liquids have ability to flow.
2. Liquids have a definite volume.
3. The intermolecular forces between liquid molecules are weaker than gases.
4. Liquids do not have a definite shape.

Answer:

The intermolecular forces of liquids are stronger than gases so option c is correct here.

• Which statement is not true about gases?

1. Gases have ability to flow.
2. Gases have a definite volume.
3. Gases have a definite shape.
4. Gases have weakest intermolecular forces between molecules.

Answer:

As gas molecules are in random motion so they don’t have a specific shape . So , option c is correct.

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