Selina solutions for Concise Chemistry [English] Class 7 ICSE chapter 2 - Physical and Chemical Changes [Latest edition]

Define physical change. Give two examples for the above changes.

Define a chemical change. Give two examples of the above changes.

What are reversible and irreversible changes ? Give one example for each.

Mention a change which is always desirable.

Mention a change which is always undesirable.

Mention a change which is always periodic.

Is burning a physical change or a chemical change? Why?

A burning candle shows both physical and chemical changes. Explain ?

State three differences between evaporation and boiling

State four differences between physical and chemical changes.

What do you observe when :

water is boiled

What do you observe when :

a piece of paper is burnt

What do you observe when :

some ice cubes are kept in a glass tumbler

What do you observe when :

solid ammonium chloride is heated

What do you observe when :

an iron nail is kept in tap water for few days

What do you observe when :

a spoon of sugar is heated in a pan

What do you observe when :

lighted match stick is brought near the mouth of the test tube containing hydrogen gas.

What do you observe when :

ime is dissolved in water.

What do you observe when: little amount of curd is added to a bowl containing warm milk and kept for five hours.

Name a chemical change which takes place in presence of:

Fill in the blank

A new substance is always formed in a _______ change.

Fill in the blank.

Melting of ice is a _______ change.

Fill in the blank.

When a candle burns, wax melts. Melting of wax is a ________ change.

Fill in the blank

Chemical change occurs as a result of __________ between two substances.

Fill in the blank

Burning of fuel is a _______ change.

Fill in the blank

Revolution of the earth around the sun is a ________ change.

Fill in the blank.

Growing of a seedling into a plant is _______ change.

State whether the following is physical or chemical changes.

glowing of a bulb -

State whether the following is physical or chemical changes.

burning of sugar — 

State whether the following is physical or chemical changes.

heating of water —

State whether the following is physical or chemical changes.

growing of a piglet into a pig — 

State whether the following is physical or chemical changes.

burning of wood -

State whether the following is physical or chemical changes.

passing electric current through a heater rod —

State whether the following is physical or chemical changes.

water cycle in nature —

State whether the following is physical or chemical changes.

respiration in living beings —

State whether the following is physical or chemical changes.

shaping a piece of glass —

State whether the following is physical or chemical changes.

lightning — 

State whether the following is physical or chemical changes.

(energy produced) dissolving sugar in water —

State whether the following is physical or chemical changes.

heating a mixture of iron filings and sulphur—

State whether the following is physical or chemical changes.

mixing oil with water —

State whether the following is physical or chemical changes.

cutting wood into small pieces — 

State whether the following is physical or chemical changes.

photosynthesis — 

State whether the following is physical or chemical change.

Digestion of food —

State whether the following is physical or chemical changes.

Melting of wax —

State whether the following is physical or chemical changes.

Boiling of an egg — 

State whether the following is physical or chemical changes.

Slaking of lime — 

Match the following:

Write true or false

Cutting of paper into pieces is a chemical change.

Write true or false

Rusting of iron is a chemical change.

Write true or false 

Earthquake is a desirable change.

Write true or false 

Melting of ice is a physical change.

Write true or false 

Burning of sugar is a temporary change.

Tick (√) the correct alternative from the choice given for the following statement.

A substance which can not sublime is

Tick (√) the correct alternative from the choice given for the following statement.

When you put some ice cubes in a glass, droplets of water are formed on the outer wall of the glass. This explains the phenomenon of

Tick (√) the correct alternative from the choice given for the following statement

Burning is a

Tick (√) the correct alternative from the choice given for the following statement

Which one of the following is volatile in nature ?

Tick (√) the correct alternative from the choice given for the following statement.

An example of both physical and chemical change is

Tick (√) the correct alternative from the choice given for the following statement.

The compound rust is a hydrated oxide of

Tick (√) the correct alternative from the choice given for the following statement

When sugar is heated, its colour changes into 

Tick (√) the correct alternative from the choice given for the following statement

A pop sound is heard when a lighted match stick is brought near the mouth of a jar. This indicates the release of gas.

Tick (√) the correct alternative from the choice given for the following statement.

When we add water to the following substances, which one will show a chemical change?

True or false 

Is melting of ice a reversible change?

True or false 

Change of seasons is a non-periodic change. 

True or false 

In a physical change no net energy change is involved.

True or false 

New substances are formed in a chemical change.

True or false 

Dissolving of a solid in liquid is a physical change. 

True or false 

Is the process of digestion a physical change?

True or false?

During a physical change energy is either given out or absorbed by the system. 

True or false?

In a chemical change, rearrangement of molecules and atoms involves some energy changes. 

Tick the most appropriate answer.

Melting of ice is a

Tick the most appropriate answer.

Rising and setting of the sun at a given place is a

 Tick the most appropriate answer.

Physical changes are

Tick the most appropriate answer.

Chemical changes involve

Tick the most appropriate answer.

Photosynthesis requires

 Fill in the blank

A change in which the substance can be brought back to its original state is called a _______ change.

 Fill in the blank

Changes that occur in nature are called ______

Fill in the blank

An earthquake is a _______ change.

 Fill in the blank

A new substance is formed in a _______ change.

Fill in the blank

Heat is ________ by a gas during the process of condensation.

Match the columns.

Write true or false

Burning of paper and formation of curd are reversible changes.

Write true or false

A natural change can also be a desirable change.

Write true or false

Deforestation is a man-made change.

Write true or false 

Decomposition of leaves is a fast change.

Write true or false 

Dissolving of solute in a solvent and rusting of iron are both physical changes.

Dissolving salt in water is a reversible change.

Ripening of fruits is a desirable change.

Melting of solid (wax) is a physical change.

Chemical changes are accompanied by changes in energy.

Photosynthesis cannot take place at night.

Name two reversible changes.

Give two examples of periodic changes.

Give an example of desirable change which can also be undesirable.

What are man-made changes ?

Sublimation is classified as a physical change. Why ?

Classify the following changes as physical or chemical.

A physical change is temporary. Explain.

State the Differences Between a Physical Change and a Chemical Change.

State the various conditions that favour the process of evaporation.

How do you say that the process of digestion is a chemical change ?

What role does energy play in initiating a chemical change ?

Solve this crossword by using the clues that follow-

Across
1. Energy in the form of sunlight is absorbed by the green plants in this process.
4. The reddish-brown substance formed over iron in the presence of oxygen and moisture.
5. This change is permanent and irreversible.
6. The process in which a solid directly changes into gaseous state.

Down
1 . It is the change that takes place in case of swinging pendulum of a clock. –
2. Occurrence of this is a non-periodic change as well as a natural change.
3. It is a physical change.

Make a list of different types of changes with example.