Olympiad Test: Matter - 2 - Class 5 MCQ

The diagram has two boxes, one in which molecules are tightly packed and the other one in which the molecules are slightly loosely packed. Here solid is slowly converting to liquid state which occurs during melting. While, boiling is the process where a liquid turns into a gas. In this state change, particles gain enough energy to move freely and spread out, which does not match the situation described in the question.

Physical changes are reversible which means we can get back to the original thing even after it has undergone change.

In the picture the heat of the sun is causing the water on the ground is being converted to the vapour form. Thus this process is evaporation.

Melting point is the temperature at which the solid melts into the liquid state.

Matter is made up of very small particles called as atoms. 

Bonfire or burning of wood is on example of chemical change where the burnt wooden logs cannot be reversed back to Solid wood. Wood once formed into ash.

Chemical changes are irreversible. After a chemical change, the thing cannot be brought back to its original form. Physical changes are reversible.

Statues are solid. They are made up of solid materials. They cannot be made up of water because water has the tendency to take the shape of its container. It has no shape.

A chemical change takes place when one form of matter changes to another kind of matter.

Freezing is when liquid changes to solid, whereas melting is the change of state from solid to liquid.

Boiling occurs at one temperature only, while evaporation may occur at different temperatures. This temperature is called the boiling point.

When the jeweller melts pure gold, he is converting solid gold into liquid gold. The gold is undergoing a physical change wherein its state is being changed but it still remains as gold. Since it is pure gold, its weight in solid form is equal to that in liquid form. Thus after melting the gold, the jeweler will get the price of 100 gm of gold only.

Gases consist of particles that are very far apart and thus move easily.

As seen in the diagram, there are small water drops on the window. These water drops can be seen as a result of the conversion of water vapour in the air back into the water form. Thus this depicts the process of condensation.

Desublimation is the process of conversion of water vapour into ice.

Melting is the conversion of ice into water.

Liquid has a definite volume but no definite shape.

Melting of ice and breaking of glass is a physical change.

The conversion of solid into gas without changing into liquid is called sublimation.

Baking of cake is an example of both chemical as well as irreversible change.