Selina solutions for Concise Physics [English] Class 8 ICSE chapter 1 - Matter [Latest edition]

The temperature of a substance remains unaffected during its change of state.

Ice melts at 100°C.

Water at 100°C has more heat than the steam at 100°C.

Evaporation of a liquid causes cooling.

Water evaporates only at 100°C.

Boiling takes place at all temperatures.

Evaporation takes place over the entire mass of the liquid.

The process of a gas converting directly into solid is called vaporization.

At high altitudes, water boils above 100° C.

The melting point of ice is 0°C.

Evaporation takes place at ...............temperature. 

.............. process is just reverse of melting. 

.............. is a process that involves direct conversion of a solid into its vapour on heating.

The temperature at which a solid convert into a liquid is called its .........

The smallest unit of matter that exists freely in nature is called ...........

Molecules of a substance are always in a state of............ and so they possess .............

Intermolecular space is maximum in .......... less in ............ and the least in .........

Intermolecular force of attraction is maximum in ............ less in .......... and the least in .............

 Match the following

The inter-molecular force is maximum in

The inter-molecular space is maximum in

The molecules can move freely anywhere in

The molecules move only within the boundary of

The temperature at which a liquid gets converted into its vapour state is called its

Rapid conversion of water into steam is an example of

Evaporation takes place from the

Boiling takes place from the

Define the term matter. What is it composed of?

State three properties of molecules of a matter.

What do you mean by the inter-molecular spaces? How do they vary in different states of matter?

What is meant by the intermolecular forces of attraction? How do they vary in solids, liquids and gases?

Solids have definite shape and definite volume. 

Liquids have definite volume but do not have definite shape.

Gases have definite volume but no definite shape.

Liquids have definite shape and definite volume.

Discuss the three states of matter solid, liquids and gas on the basis of molecular model.

What do you mean by the change of state? Write the flow chart showing the complete cycle of change of state.

Differentiate between melting point and boiling point, giving atleast one example of each.

Describe the process of condensation with examples.

Describe the process of sublimation with examples.

Explain the term Melting.

Explain the term Melting Point.

Describe an experiment to demonstrate that a substance absorbs heat during melting without change in its temperature.

Explain the term vaporization.

Explain the terms boiling point.

A liquid can change into vapour state at a fixed temperature.

A liquid can change into vapour state at all temperatures.

Name the processes involved in two cases.

Some ice is taken in a beaker and its temperature is recorded after each one minute. The observations are listed below

From the above observations, what conclusion do you draw about the melting point of ice?

Describe an experiment to demonstrate that water absorbs heat during boiling at a constant temperature.

State the melting point of ice.

State the boiling point of water.

What is evaporation?

State three factors which affect the rate of evaporation of a liquid.

Wet clothes dry more quickly on a warm dry day than on a cold humid day. Explain.

Water in a dish evaporates faster than in a bottle. Give reason. 

Why are volatile liquids such as alcohol and spirit stored in tightly closed bottles?

A certain quantity of water is heated from 20°C to 100°C. Its temperature is recorded after each 1 minute. The observations are:

Why is cooling produced on evaporation of a liquid?

Explain with an example to demonstrates that when a liquid evaporates, it takes heat from its surroundings.

Give two applications of evaporation.

Explain why in hot summer days water remains cool in earthen pots.

A patient suffering from high fever is advised to put wet clot strips on his forehead. Why?

What do you mean by sublimation? Explain with an example.

Why does the size of naphthalene balls decrease when left open?

Describe an experiment to demonstrate the process of sublimation.