CHEMISTRY [1 Mark Question Answer]

do it yourself.

Glass, stone, pen

Oxygen, hydrogen, nitrogen

Naphthalene, camphor, dry ice.

boiling

melting

sublimation

vaporisation

: Change of vapours on cooling to liquid is called liquefaction.

: The fixed temperature at which a liquid starts changing into gaseous state is called its boiling point. The temperature remains constant till the whole of the liquid changes into gaseous state

The fixed temperature at which a solid changes into a liquid at a given pressure is called its melting point. The temperature remains constant as long as the conversion is going on.

The phenomenon of intermixing or spreading of gaseous molecules is called diffusion

The change of solid on heating to vapours directly and vice-versa without passing through the liquid state is called sublimation

The process by which a substance in gaseous state changes into its liquid state is called condensation

The heating process by which a liquid changes into its vapour state is called vaporisation.

The heating process by which a solid changes into the liquid state is called fusion.

Two conditions are :

1. Change in temperature
2. By applying pressure

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

When a substance is heated, it can cause.

1. Interconversion of states of matter.
2. Thermal expansion of the substance.
3. Chemical change.

The zig-zag motion of particles suspended in a medium is called Brownian movement

The phenomenon of intermixing of particles of one kind with another kind is called diffusion.

The force of attraction between particles of the same substance is called cohesive force.

When 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 is because Gases can diffuse or flow in all directions.

When a teaspoon of sugar is added to half a glass of water and stirred, the water level in the glass remains unchanged because the sugar particles are adjusted between the water molecules as inter-molecular gaps are more in liquids.

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

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

Scent fumes (molecules) being gases fill the spaces between air molecules and the molecules of air fill the spaces between scent molecules due to diffusion, fumes spread into a room

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

Solids: Common salt, wax, stone, sugar, coal, butter, copper.
Liquids: milk, mercury, blood, coconut oil.
Gases: Oxygen, L.P.G, carbon- dioxide.

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

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

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

Atoms may or may not have independent existance. While molecules have independent existence.

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

When we invert the bottle and blow air into the bottle throw the side opening. It creates high pressure inside the bottles and the egg is kicked out of the bottle.

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

Natural matter: Wood, silk, coal, water, fruits.
Man made matter: Plastic, medicines, detergents, ceramic, cotton, glass, nylon.

Anything that has mass and occupies space is called matter.

A bottle of perfume on opening evolves an odour because gases diffuse very easily and odour spreads over a large distance.

Every pure substance has a fired melting point or boiling point.

Sugar is soluble in water whereas talcum powder is not.

The matter is the basic substance of which all materials are made of.