Is Matter Around Us Pure?

Learn Easily Foundation, Basics, important Solved Questions and Answers from CBSE NCERT Science Subject Class 9

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আপনি এখানে শিখবেন এই অধ্যায়ে এবং বিষয়ের ফাউন্ডেশন অংশটা, এই বিষয়টিকে সহজ-সরলভাবে পড়িয়েছেন বিশেষজ্ঞ শিক্ষক ভিডিও লেকচার এর মাধ্যমে এবং এই পুরো অধ্যায়কে চার ভাগে খন্ডিত করে  আপনার জন্য তৈরি করা হয়েছে

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Definition, Important Terms, Explanation in Simple Words for Fast Learning

Is Matter Around Us Pure?

In chemistry, we considered a substance to be pure when it is made up of one type of constituent particle other words a substance is a pure single form of a matter

Depending upon the chemical composition, matter can be classified into elements, compounds that Are Pure substances that are non-separable by physical and mixtures separable by physical methods like sublimation, evaporation etc

Pure substance
A substance that consists of only a single type of constituent particles is called a pure substance
Based upon the nature of constituent particles a pure substance can be classified into two types that are elements and compounds


The term element was first used by Robert Boyle in the year 1661. According to a French chemist ‘Lavoisier, an element is a basic form of matter that cannot be broken down into simpler substance by chemical reaction’
Till now 118 elements have been discovered out of these 92 natural elements and others are man-made, they can be broadly classified as metal, nonmetals and metalloids

1. Metals
Metal is an element that is malleable that means it can be hammered into thin sheets, it is also ductile that means it can be drawn into wires and also so nervous that means it can make a a ringing sound when hit and also it can conduct heat and electricity

They are lost that means they are Shiny and have a unique colour
Mercury is the only metal that is liquid at room temperature
Gallium and caesium because of their very low melting points remain in liquid state at a temperature slightly above room temperature [303k]

2. Non metals
A non-metal is an element that is neither malleable nor ductile and does not conduct heat or electricity. They display various colours
Examples of non-metals are hydrogen, oxygen, iodine, carbon, bromine

3. Metalloids
Elements having intermediate properties between those of metal and nonmetals are called metalloids
Examples of metalloids are Boron, silicon and Germanium

A compound is a substance composed are comprised of two or more elements chemically combined with each other in a fixed proportion
Examples of compounds are the water- h2O, methane ch4, carbon dioxide CO2, uh Ammonia NH3

Mixtures are comprised of more than one type of pure form known as substance. Most of the matter around us exist in the form of a mixture where two or more pure components are mixed together

Examples of mixtures are are water, soil, salt and pepper

Types of mixtures
1. Homogenus mixture
A mixture where the constituency are the components are mixed together uniformly and distributed throughout that is without any clear boundary of separation is called homogenous mixture
Here are the constituents of the components cannot be seen with naked eyes or under a microscope
Some examples of how much is mixture Sar sugar water solution, air, crude oil, biogas and alloy

2. Heterogeneous mixture
A mixture that does not have uniform composition and the constituencies can be seen as separate entities mixed together is called heterogeneous mixture. The components can be seen with naked eyes and under microscope

Examples of heterogeneous mixtures are
Sugar mixed with sand
Water mixed with oil

Differences between compound and mixtures

Specific elements are present in specific ratio
Components lose their individual properties when mixed in a a compound
Components cannot be separated by simple physical methods
Large quantity of energy is required to change the formation of the compound
Compound is always homogenous in nature

The components are mixed in in random ratios
Chemical reaction does not take place during its formation
Components retain their individual properties
Components can be separated by simple physical methods
Energy does not take place during the formation of decomposition of the mixture
A mixture can be homogenous and heterogeneous in nature


A homogenous mixture of two or more substances is called a solution. A solution might be called a true solution

Soda water, salt solution, sugar solution are all examples of of solution

In solution there is homogeneity at particle level that means that particles of the substance dissolved together and evenly distributed in the solution and hence they cannot be distinguished from each other

There are two main components of a solution
1. Solvent
Dissolving face- the component which is usually present in larger amount of the solution that dissolves the other component within it is called the solvent

2. Solute – dissolved phase

The component which is present in lesser quantity of the solution and which gets dissolved in the solvent is called the solute

Alloys are mixtures of two or more metals or a metal and non metal and it cannot be separated into their components by physical methods
Still and alloy is also considered as a mixture because it shows the properties of its constituents and can have variable composition. For example when we take brass is a mixture of approximately 30% zinc and 70% copper

Properties of a solution
Some of the important properties of a solution are as follows:
1. Solution is a homogenous mixture
2. The particles of a solution are less than 1 NM
3. Due to very small particles they do not scatter a beam of light passing through the solution so the path of light is not visible in the solution
4. A solution is stable that is the solute particle do not settle down when the solution is left undisturbed. The solute particles cannot be separated from the mixture by the process of filtration

Concentration of a solution
Concentration of a solution is equal to the amount of solute present in a given amount of mass or volume of solution for the amount of solute dissolved in a given mass or volume of solvent.
In solution the relative proportion of solute and solvent does vary
Depending upon the amount of solute present in a given amount of solvent it can be classified as follows:

1. Saturated solution
Saturated solution is a solution where no more amount of solvent can be dissolved at a given temperature
The amount of solute present in the saturated solution at a given temperature is called solubility

2. Unsaturated solution
Unsaturated solution it is a solution where the amount of solute contained in a solution is less than the saturation level. In this solution you can add more solute which can dilute in the solution, you can add as much solute as you want it until you reach the saturation level of the solution

Expressing the concentration of a solution

The method by which the concentration of a solution can be expressed are
[ are put the formula for mass by mass percentage mass by volume percentage please]


Suspension is a heterogeneous mixture in which the solute particles do not completely dissolve but remain suspended throughout the bulk of the medium

Examples of suspension are:
Water mixed with oil
Sand mixed in water
Chalk powder mixed with water

Properties of suspension
1. Suspension is a heterogeneous mixture
2. Different particles can be seen with naked eyes
3. Is particles scatter a beam of light which passes through making the particles visible and this effect is called tyndall effect
4. Suspension is unstable in nature that means the solute particles settle down when suspension is left undisturbed
5. The constituents of suspension can be separated by the process of filtration

Colloidal solution
A colloid or a colloidal solution is a mixture that e e is actually heterogeneous but appears to be homogenous as particles are uniformly spread throughout the solution
Examples of Colloidal Solutions are
Are milk
Shaving cream

Properties of a colloid
1. Colloid is a heterogeneous mixture
2. Size of individual particles of colloid is too small to be seen by naked eyes
3. Colloidal solution components are big enough to scatter a beam of light passing through it making its path visible
4. Colloidal Solutions are quite stable and particles do not settle down when the colloid is left undisturbed
5. Particles of colloid can pass through a filter paper therefore a colloidal solution cannot be separated by the process of filtration. But they can be separated by the process called centrifugation

Common examples of colloid
Colloidal Solutions are classified into three states that is solid liquid or gas

Separating the components of a mixture
Many of the natural substances are not chemically pure and can be separated by using different methods of separation to get individual components from the mixture. In order to separate the components from a mixture, many methods can be utilised the nature of the methods utilised to separate the mixture depends on the nature of components present in the mixture

Heterogeneous mixtures can be separated into their components by simple physical methods like handpicking filtration at 17 that we use in our day to day life. Sometimes special techniques might be used to separate the components of mixtures



Evaporation is a process of conversion of a substance from a liquid state to gaseous state it and the substance is said to be volatile if it gets evaporated
This method is primarily used to separate volatile components from non-volatile components of a mixture. On heating, the mixture of the volatile component evaporates leaving behind non-volatile components and hence gets separated

Centrifugation is a process in which two components having difference in densities can be separated, this method is based on the principle that denser particles are forced to the bottom and the lighter particles stay at the top when spun rapidly.
A device used to separate liquid from solid by spinning is called a centrifuge

Centrifugal machines are commonly used for this method the machine can be rotated by hand or using a machine

Centrifugal machines are primarily used to separate ghee from milk
Washing machine to remove and squeeze out water from wet clothes

Separation By Using Separating Funnel

Separation is a method that is used to separate a mixture of two immiscible liquids. This method is based upon the principle that immiscible liquids separate out in layers depending on their densities.

Separating funnels are used in the separation of a mixture of oil and water
And it is also used during the extraction of iron from its iron ore


Sublimation is a process in which some solids which are having the tendency to sublime on heating that is the convert directly from solid to gaseous of vapour state without passing through the liquid state
A mixture containing such solid with any other normal solid can be separated by the process of sublimation

For example, solids that sublime are camphor, naphthalene, iodine

The term chromatography is based on the Greek word Chroma which means colour, this technique is used for separation of colour.
Chromatography is the process used for the separation of those solutes that are dissolved in the same solvent. The separation of different components of mixture is is dependent upon their different solubilities in the same solvent

The ink we use has water as solvent and the dye is soluble in it as the water rises on the filter paper it takes the dye particles with it
Usually dye is a mixture of two or more different colours. The coloured component that is most soluble in water rises faster in this way the colour is separated from its solvent

Applications of chromatography:
1. It helps in separating drugs from blood
2. It helps to separate pigments from natural colours
3. It helps to separate colours which are present in the dye

Distillation is a process of separating two aur more miscible liquids which boil without decomposition and have different boiling points
Distillation involves the conversion of a liquid into vapour followed by condensation of vapour back into the form of liquid
Distillation is a process which is used only if the liquids have difference in their boiling points of more than 25 Kelvin

Fractional distillation
Where the differences in the boiling points are less than 25 Kelvin the process of fractional distillation is used which means
For example separation of different types of gases from the air
Separation of different types of petroleum products from crude oil

The Apparatus used for fractional distillation is similar to that of simple distillation except that a fractionating column is installed between the two distillation flask and condenser
A simple fractionating column is a kind of tube that is packed with glass beads. The beach provides a larger surface for vapours to cool down and condense repeatedly at a faster speed

Separation Of Different Gases Present In Air


Air is a homogenous mixture that can be separated into its components by fractional distillation. For this specific purpose, the air is compressed by increasing the pressure and it is given time to cool down to a very low temperature which causes the air to become liquid. This liquid air is allowed to warm up slowly and gradually in a fractional distillation column where different gases present in the air gets separated at different heights depending upon their boiling point

Crystallization is a process where the separation of pure substances from their impure form is done
Crystallization is a process that helps a separate pure solid in the form of its crystal from a solution and this process is primarily used to purify solids for example the salt we get from seawater can have a lot of impurities but we use the process of crystallization to remove the impurities

Crystallization technique is better compared to simple evaporation technique because:
1. Some solids decompose or may get charged during heating from liquid to two solid-state
2. Impurities may remain diluted in the solution even after filtration which might contaminate the solid during evaporation

What is the application of crystallization?
1. Crystallization technique is primarily used in the purification of salt obtained from seawater
2. Crystallization technique is primarily used to separate crystals of alum from impure samples

Purification of drinking water

The process of purification of drinking water is done on a large scale to provide Portable water to the human population residing in a country. A of large number of impurities are therein in water which is taken from the Reservoir and it requires purification before it is drinkable

There are various processes that are used to filter water some of them are as follows:

1. Sedimentation is a process that helps us to remove suspended solids where the water is allowed to stand for some time so the impurities that settle down at the bottom or float on the surface of the water
2. Loading with alum helps us to remove small particles like clay soil which is present in the colloidal state. Alum helps to neutralize the clay particles and coagulate clay at the bottom of the tank
3. Filtration helps us to remove dissolved solid in water through filtration tank which comprises of three layers
Coarse gravel at the bottom, find Global at the centre and find the sun at the top acts as a filter
Impure water is introduced from the bottom so that it is are retain in these three layers of gravel pure water then goes to the top and send to the chlorination tank
4. In the chlorination tank all the bacterias are element the water where the water is treated with bleaching powder now this water is drinkable and can be consumed by humans

Physical and chemical changes

Physical changes
Properties which can be observed and I are specified like colour hardness rigidity fluidity density melting point are called physical properties
These changes occur without a change in composition and in chemical nature and these properties are called physical changes
The interconversion of states of physical change that is when water changes into ice its physical shape changes but it’s chemically the same

Chemical changes

During chemical changes, one substance reacts with another substance to undergo a chemical change in composition
Chemical changes bring along a new property and a new substance is obtained
Chemical changes are also called a chemical reaction for example when water and cooking oil are both liquid their chemical characteristics are different their different in order and inflammability

Petroleum Oil burns in the air where does water extinguishes fire that means that the chemical properties of oil and water are completely different

MCQ SHort Questions (1 Marks)

অতি সংক্ষিপ্ত প্রশ্নোত্তর - Short Answers & Questions (3-4 Marks)

ব্যাখ্যা ভিত্তিক সংক্ষিপ্ত প্রশ্নোত্তর - Long Answers & Questions (5-6 Marks)



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