PHYSICS [1 Mark Question Answer]

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

The space between any two consecutive molecules of a substance is called intermolecular space

The change in the state of matter of a substance from solid to liquid or from liquid to gas is brought by imparting heat energy to it at a constant temperature.

The particles in a substance are not at rest (in motion), and they move randomly in all possible directions in a zig-zag Path

The spacing between particles of a matter is called inter-molecular space.

Matter is defined as anything which occupies space and has mass. It can be perceived by our sense of smell, touch, sight, hearing, and taste.
Matter is composed of tiny particles known as atoms.

Glass, stone, pen.

Paper, sugar.

Naphthalene, camphor, dry ice.

Conversion of water into steam is boiling.

Conversion of ice into water ismelting.

Disappearance of camphor issublimation.

Formation of water vapour from water isvaporation.

Gas

Solid

Liquid

The molecules can move only when there are gaps or spaces between them, this space is called intermolecular space.

The molecules of matter are always in motion and attract each other with a force called the intermodular force of attraction due to which they are held together.

Atoms may or may not have an independent existence. Molecules have an independent existence.

Molecules are made of atoms. Molecules exhibit the properties of that kind of matter and have independent existence.

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

Mass of a body does not change with change in gravity. So the mass of a body will remain the same on the moon.

Weight of body on moon = 1 / 6 th of its weight on earth
∴ Body will weigh 1 / 6 × 6 = 1 kg on moon

Mass is the quantity of matter contained in the body.

If we put a drop of red ink in a glass of water, its particles diffuse with particles of water slowly but continuously and the water turns red.

This shows that gases can fill up all the space that they get, and they have neither a fixed shape nor a fixed volume. They have no free surfaces, either.

The molecules of the liquid are loosely packed and the intermolecular force of attraction is small but a number of molecules in it remains the same. Hence liquids have a definite volume but no definite shape.

The molecules of air are far apart i. e. large gaps and we can walk through the air easily.

Intermolecular force of attraction is least and intermolecular spaces are very large, hence gases can fill up the space available to them.

The molecules of liquids and gases are far apart i.e. have more gaps, intermolecular attraction force is very less as compared to solids, hence liquids and gases can flow but solids do not like gaps in solid molecules is a less and molecular force of attraction very strong.

Take two similar balloons and inflate them equally. Suspend one balloon to the left of a metre scale and the other one to the right of it, as shown in the figure below. Balance the scale in the middle with the help of a peg.

A molecule is the smallest part of a compound that exists independently.

An atom is the smallest part of an element that takes place in a chemical reaction.

It is defined as that pure substance that contains only one type of atoms e.g. hydrogen, chlorine.

The force of attraction between the molecules of a given substance is called intermolecular force.

Anything that has mass and occupies space is called matter.

Electricity neither has mass nor it occupies space. Besides, it can not be seen by our eyes. This is why electricity is not considered a matter

Pure substances consist 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.

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

In liquids, the intermolecular force is weaker than that of solids. So molecules in liquids can slip over one another and liquids can flow, unlike solids.

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

When a solid is heated, its molecules gain energy and vibrate faster. A stage comes, when they overcome the intermolecular force of attraction and start moving from each other. This results in the melting of solid.

The amount of space occupied by a matter is called its volume.

Molecules of a liquid are held by weak intermolecular förces. This force is strong enough to hold the molecules together but not strong enough to hold them at fixed positions. As a result, liquids have a fixed volume but not shape.

General Properties Of A Solid :

1. Solids are hard that is, they have a definite shape and volume.
2. Solids are generally incompressible.
3. Solids are rigid, that is, they do not flow.

As a liquid is heated, its particles start gaining energy and move more vigorously which increases the gaps between the particles and decreasing the force of attraction. Ultimately a liquid changes into the gaseous state.

Two conditions are: change in

1. Temperature
2. Pressure

The process by which matter changes from one state to another and back to the original state, without any change in its chemical composition.