Physical Change and Chemical Change Class 7 NCRT Science Ch 6 Full Explanation with Definition and Example.
Friday 25 December 2020
physical changes and what's chemical change.
Covered topics.
What is physical change and chemical changes.?
What is slow change?
what is fast changes?
Types of changes?
How many types of changes are there?
How many types of changes are there?
There are three types of changes are.
1)slow and fast change
2)Reversible and irreversible change
3)physical and chemical change
Now let's study them in detail one by one.
What is physical change?
1)Physical changes.
Ans A changes during which no new substance are formed is understood as a physical changes
so let's understand more about physical changes with the assistance of example.
Simple Example of physical changes are.
1)Bending a copper wire into different
shapes may be a phase change s here are copper doesn't become another substance that's way it's physical change.
2)Breaking of chalk may be a physical changes because by doing no new substance is made.
3)Breaking of glass tumbler may be a phase change here when the glass breaks its size shapes and skill to carry water and lost but no new substance gets formed
I hope you all understand what's physical changes so let's examine chemical changes.
2)Chemical changes
These sort of changes during which a replacement substance gets formed is named a chemical process
So let's understand more about chemical process with the assistance of following examples.
Easy Example of chemical changes.
1)Burning of wood is chemical process
before the wood is burnt it's hard and brown in colour after burning it's produces smoke and changes into wood charcoal and ash which are black and powdery.
2)change of milk into curd may be a chemical process milk may be a liquid after curding changes into a semi solid material which features a different tast
3)Rusting of iron may be a chemical
changes iron is grey solid which gets attracted by a magnet after rusting the surface of iron gets covered with a brown solid which isn't not attracted by magnet
So guys I hope you all understand the term meaning of phase change or chemical process so let's examine some.
Difference between physical changes
and chemical changes.
Physical changes
No new substance is made the substance may change its appearance physical state
Ex tearing of paper
Freezing of water
Glowing of bulb
Melting of ice
Chemical changes
new substance with different properties is made.
Example of chemical changes
Burning wood
Souring milk.
Mixing acid and base.
Digesting food.
Cooking an egg.
Slow and fast change
Let's compare these two types of changes
Slow change
The change, that takes place in a longer duration of time, time are called slow changes.
Some examples.
Changes of seasons
Growth of a planets
Rusting of iron
Fast changes
The changes that takes place quickly or in other duration of time are called fast changes.
Some examples of fast changes are:
Burning of paper
Lighting of bulb
Cutting of apple
Reversible and irreversible changes.
A changes in which the substance obtained can back to the original forms is called a reversible change.
These are temporary changes which can be reversed when the causes of the changes is removed.
Some examples of reversible change are
Freezing of water
Evaporation
Stretching of rubber string.
Irreversible changes
A changes in which the substances produced cannot gets back to the original forms is called an irreversible changes.
These are permanent changes which cannot be reversed even if the cause of the changes is removed.
Some examples of irreversible changes are :
Changing of dough into chappatis.
Making a dress from single pieces of cloths.
getting older.
Questions and answers realeated to physical changes and chemical changes and reversible change and irreversible changes.?
Q1Burning of fule is which changes ?
Ans Fast change
Q2Rusting of iron is which change ?
Ans slow change
Q3Glowing of a bulb is a reversible change
Ans False
Q4Deforestation is an reversible change ?
Ans False
Q5 Burning of paper is a temporary change?
False
Q6Cutting of an apple is chemical change?
False
Q7Making of fruit salad is a chemical change?
Ans False
Q8Changing milk into curd is a physical change ?
Ans False
Q9Evaporation of water is a
Ans Physical change
Q10One example of irreversible changes ?
Growth of a child