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Selina solutions for Class 7 Chemistry chapter 2 - Physical and Chemical Changes

Selina Concise Chemistry - Middle School for Class 7 (2018-19 Session)

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Selina Selina Concise Chemistry - Middle School Class 7 (2018-19 Session)

Selina Concise Chemistry - Middle School for Class 7 (2018-19 Session) - Shaalaa.com

Chapter 2: Physical and Chemical Changes

Chapter 2: Physical and Chemical Changes solutions [Page 0]

(a) Define:
(i) a physical change
(ii) a chemical change
(b) Give two examples for each of the above two changes.

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

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.

Mention a change which is always

 

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.

Name a chemical change which takes place in presence of:

Chapter 2: Physical and Chemical Changes solutions [Page 0]

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

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

Fill in the blank.

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

Fill in the blank

Burning of a 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 are physical or chemical changes.

glowing of a bulb -

State whether the following are physical or chemical changes.

burning of sugar — 

State whether the following are physical or chemical changes.

heating of water —

State whether the following are physical or chemical changes.

growing of a piglet into a pig — 

State whether the following are physical or chemical changes.

burning of wood -

State whether the following are physical or chemical changes.

passing electric current through a heater rod —

State whether the following are physical or chemical changes.

water cycle in nature —

State whether the following are physical or chemical changes.

respiration in living beings —

State whether the following are physical or chemical changes.

shaping a piece of glass —

State whether the following are physical or chemical changes.

lightning — 

State whether the following are physical or chemical changes.

(energy produced) dissolving sugar in water —

State whether the following are physical or chemical changes.

heating a mixture of iron filings and sulphur—

State whether the following are physical or chemical changes.

mixing oil with water —

State whether the following are physical or chemical changes.

cutting wood into small pieces — 

State whether the following are physical or chemical changes.

photosynthesis — 

State whether the following are physical or chemical changes.

Digestion of food —

State whether the following are physical or chemical changes.

Melting of wax —

State whether the following are physical or chemical changes.

Boiling of an egg — 

State whether the following are physical or chemical changes.

Slaking of lime — 

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.

Chapter 2: Physical and Chemical Changes solutions [Page 0]

Tick (√) the correct alternative

A substance which can not sublime is

  1. iodine
  2. camphor
  3. sugar
  4. dry ice

Tick (√) the correct alternative

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

  1. melting
  2. freezing
  3. condensation
  4. evaporation

Tick (√) the correct alternative

Burning is a

  1. slow process
  2. fast process
  3. natural process
  4. none of the above

Tick (√) the correct alternative

Which one of the following is volatile in nature ?

  1. common salt
  2. petrol
  3. water
  4. milk

Tick (√) the correct alternative

An example of both physical and chemical change is

  1. burning of candle
  2. melting of ice
  3. cooking of food
  4. blowing of bulb

Tick (√) the correct alternative

The compound rust is a hydrated oxide of

  1. copper
  2. aluminium
  3. iron
  4. gold

 

Tick (√) the correct alternative

When sugar is heated, its colour changes into

  1. red
  2. brown
  3. black
  4. grey

Tick (√) the correct alternative

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

  1. oxygen
  2. hydrogen
  3. nitrogen
  4. water-vapour

Tick (√) the correct alternative

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

  1. salt
  2. sugar
  3. oild
  4. quick lime

Chapter 2: Physical and Chemical Changes solutions [Page 0]

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. 

Chapter 2: Physical and Chemical Changes solutions [Page 0]

Tick the most appropriate answer.

Melting of ice is a

  1. reversible change,
  2. irreversible change,
  3. chemical change,
  4. none of these

Tick the most appropriate answer.

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

  1. periodic change.
  2. undesirable change.
  3. physical change.
  4. reversible change

 Tick the most appropriate answer.

Physical changes are

  1. permanent.
  2. periodic,
  3. temporary
  4. irreversible.

Tick the most appropriate answer.

Chemical changes involve

  1. change in shape.
  2. change in size.
  3. change in molecular composition.
  4. none of these

Tick the most appropriate answer.

Photosynthesis requires

  1. heat energy.
  2. wind energy,
  3. sunlight.
  4. sound energy.

Chapter 2: Physical and Chemical Changes solutions [Page 0]

 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.

Chapter 2: Physical and Chemical Changes solutions [Page 0]

Match the columns.

 Column  A      Column B 
1. a change which cannot be easily reversed  a. man-made change 
2 a change that repeats itself at regular intervals b. chemical chang 
3. a change that is made by humans  c. physical change
4. a change in which the original substance cannot be obtained   d. periodic change 
5. a change where no new substance is formed  e. irreversible change 
  f . slow change

 

Chapter 2: Physical and Chemical Changes solutions [Page 0]

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.

Chapter 2: Physical and Chemical Changes solutions [Page 0]

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.

Chapter 2: Physical and Chemical Changes solutions [Page 0]

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 ?

Chapter 2: Physical and Chemical Changes solutions [Page 0]

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 ?

Chapter 2: Physical and Chemical Changes solutions [Page 0]

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.

Chapter 2: Physical and Chemical Changes

Selina Selina Concise Chemistry - Middle School Class 7 (2018-19 Session)

Selina Concise Chemistry - Middle School for Class 7 (2018-19 Session) - Shaalaa.com

Selina solutions for Class 7 Chemistry chapter 2 - Physical and Chemical Changes

Selina solutions for Class 7 Chemistry chapter 2 (Physical and Chemical Changes) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CISCE Selina Concise Chemistry - Middle School for Class 7 (2018-19 Session) solutions in a manner that help students grasp basic concepts better and faster.

Further, we at Shaalaa.com are providing such solutions so that students can prepare for written exams. Selina textbook solutions can be a core help for self-study and acts as a perfect self-help guidance for students.

Concepts covered in Class 7 Chemistry chapter 2 Physical and Chemical Changes are Concept of Physical and Chemical Changes, Chemical Change - Formation of a New Product with New Properties., Differentiating Between Physical and Chemical Change., Classification as Physical and Chemical Change., Types of Change Involved When There is a Change of State of Matter, Types of Change Involved When There is a Change of Energy..

Using Selina Class 7 solutions Physical and Chemical Changes exercise by students are an easy way to prepare for the exams, as they involve solutions arranged chapter-wise also page wise. The questions involved in Selina Solutions are important questions that can be asked in the final exam. Maximum students of CISCE Class 7 prefer Selina Textbook Solutions to score more in exam.

Get the free view of chapter 2 Physical and Chemical Changes Class 7 extra questions for Chemistry and can use Shaalaa.com to keep it handy for your exam preparation

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