Is Matter Around Us Pure

False,

(i) Milk

(ii) Mixture of different colours - Paint

(iii) Mixture of different gases-Air.

Air is made of different gases. Hence air is a mixture of gases.

Metal - Mercury exists as liquid at room temperature.

Non-metal - bromine exists as liquid at room temperature.

Soft Metal - Sodium.

Hard non-metal - Diamond.

Diamond is a non-metal which is a good conductor of electricity.

Mercury is a pure substance (non-metal) and conducts electricity.

Solid non-metal

Liquid non-metal - Bromine

Gaseous non-metal - Hydrogen

(a) Malleability is the property which allows metals to be hammered into thin sheets. For example- Aluminum.

(b) Ductibility is the property which allows metals to be drawn into wires. For example - Copper.

Non-metals show the property of brittleness. A material is brittle if, when subjected to stress, it breaks without significant plastic
deformation.

Malleable metals, like copper and nickel, are able to be stretched out into thin wires. This is known as Malleability.

Copper, nickel and tin are a few metals that are able to be pounded into thin sheets and able to be made into thin wires. This is known as Ductility.

When atoms move in different ways and can be pounded or stretched, they are both malleable and ductile.

Non-metals show the property of brittleness. A material is brittle if, when subjected to stress, it breaks without significant plastic
deformation.

Metals produce ringing sound when beaten, i.e. metals are sonorous.
This is the reason that bells are made of metal.

Metals are lustrous because of the presence of free electrons. ... These electrons can freely move about the surface of metal and are therefore called mobile electrons. Because of these mobile electrons, light falling on the surface of a metal is not transmitted but is reflected, and hence the metals appear lustrous.

Substances which are made of two or more materials and which can be separated by physical methods are known as mixtures, such as mixture of salt and water, mixture of sugar and water, mixture of different gases, air, etc. In a mixture, components do not combine chemically or through any chemical change. In a mixture, components do not lose their properties.

The properties of a compound are entirely different from those of its constituents. Hence above statement describes a compound.

Element- Nitrogen

Compound- Water

Mixture- Air

Mixture of two or more substances with one phase only, i.e. having no distinct boundary of constituent particles are called solution. For example, solution of sugar and water, solution of salt and water, lemonade, soft drinks, etc. Solution is a homogeneous mixture of two or more substances an ordinary mixture is made up of two or more matters and which can be separated by physical methods, such as mixture of different gases, air. In a mixture, components do not combine chemically or through any chemical change.

Some element have intermediate properties of the metals and non-metals. The elements which exhibit the properties of metals as well as non-metals, are called metalloids. Example: Boron, Silicon, Germanium etc.

(a) atoms

(b) mixture; compound

(c) mixture

(d) boron; silicon; germanium

(e) metals

“Shake well before use”. This is because the particles of indigestion mixture settle down at the bottom of the bottle.

(a) Suspensions

(b) Colloids

(c) True solutions

(d) As A and B are suspensions and colloids, they will show Tyndall effect

(e) (i) Example of suspension is Chalk-water mixture

(ii) Example of colloid is Soap solution

(iii) Example of true solution is Salt solution

(a) Chemical change; Because the properties of products B and C are entirely different from those of solid A and water

(b) Physical change; Because the product E shows the properties of both, solid D and water

(c) Sodium; Sodium hydroxide and Hydrogen

(d) Ammonium chloride

(e) Evaporation

(a) Unsaturated solution

(b) Saturated solution

(c) Some of the dissolved solid will separate from the solution and settle down a the bottom of the beaker; Because the solubility of solid decreases on cooling

(d) Solubility

Solubility at 40C = 41g

Solubility = Solid dissolved in 100g of water in a solution

So, mass of ammonium chloride needed to make a saturated solution of ammonium chloride in 50 g of water = 41/2 = 20.5g

A mixture of sulphur and carbon can be separated by the solvent extraction method. Carbon disulphide or carbon tetrachloride is used as a solvent. The sulphur component gets dissolved in solvent and undissolved carbon is separated by filtration. The dissolved sulphur can be evaporated from the solution.

A mixture of sodium chloride and ammonium chloride can be separated out using the process of sublimation. For this, the mixture is heated in a China dish.

We can separate the sublimating substance (Naphthalene / Anthracene / Camphor / Ammonium chloride) from the mixture of naphthalene and common salt

through the process of sublimation.

We can separate the sublimating substance (Naphthalene / Anthracene / Camphor / Ammonium chloride) from the mixture of anthracene and copper sulphate

through the process of sublimation.

We can separate the sublimating substance (Naphthalene / Anthracene / Camphor / Ammonium chloride) from the mixture of salt and camphor through the process of sublimation.

When a crane fitted with a powerful electromagnet is lowered on to the heap of waste materials, then the scrap iron objects get separated. The crane is then moved up and away to drop these scrap iron objects at a separate place.

We can separate the sublimating substance (Naphthalene / Anthracene / Camphor / Ammonium chloride/ Iodine) from the mixture of iodine and salt through the process of sublimation.

Fractional distillation is the process to separate a mixture of two miscible liquids (like acetone and water).

Difference in boiling points enables separation of two miscible liquids by fractional distillation.

Alcohol and water can be separated by fractional distillation.

Oil and water can be separated by using a separating funnel.

(a) False

(b) False

Air is the source from which nitrogen and oxygen are obtained on a large scale as air contains large quantities of both of these gases.

Air comprises of nitrogen, oxygen, carbon dioxide and argon as major components. Since air is the cheapest source of these gases, thus these are extracted from air at large scale. After liquefaction of air by repeated compression and cooling; nitrogen, oxygen, carbon dioxide and argon are extracted using fractional distillation.

If a mixture contains iron as one of the constituent, it can be separated by using magnet. A mixture of iron filing and saw dust can be separated by using magnet. This is because iron filling are attracted by a magnet but saw dust is not attracted by a magnet.

Ammonium chloride and sodium chloride are two solid substances whose mixture can be separated by sublimation.

Salt and water is one pair of substances whose mixture can be separated completely by distillation

The mixture containing chalk powder and water is allowed to get filtered.

(Filter paper can be used for filtration). After filtration, the retentive obtained is chalk and the filtrate obtained is water without chalk.

The retentive is allowed to get dried and thence, chalk is obtained in powder form. In this manner, we can separate chalk powder from water.

Salt is soluble in water whereas sand is insoluble in water. This difference in solubility of salt and sand in water is used to separate them. The mixture of salt and sand is taken in a beaker and water is added to it. The mixture is stirred to dissolve the salt in water. The sand remains undissolved. The salt solution containing sand is filtered by pouring over a filter paper kept in a funnel. Sand remains as a residue on the filter paper and salt solution is obtained as a filtrate in a beaker kept below the funnel.

The solution of common salt and water is taken in a china dish and heated gently by using a burner. The water present in salt solution will form water vapours and escape into atmosphere. When all the water present in the solution of common salt and water gets evaporated, then common salt is left behind in the china dish as a white solid. The process of evaporation is used on a large scale to obtain common salt from sea water.

The process of centrifugation is used in dairies to separate cream from milk. The milk is put in a closed container in big centrifuge machine. When the centrifuge machine is switched on, the milk is rotated at a very high speed in its container. Due to this, the milk separates into cream and skimmed milk.

The process of centrifugation is also used in washing machines to squeeze out water from wet clothes and make them dry.

A heterogeneous mixture of a solid (tea leaves) and a liquid(tea) can be separated by the process of filtration. Pour the tea through a strainer. The tea leaves will get strained and clear solution of tea is obtained.

The mixture of alcohol and water can be separated by the process of distillation. The mixture of water and alcohol is taken in a flask and is heated. Since the boiling point of water is less than that of alcohol, water vaporizes fast and it gets condensed in the condenser and is collected. After that alcohol gets condensed and the mixture is separated.

Those liquids which do not mix with each other and form separate layer are called immiscible liquids. For Ex: Oil and water, Petrol and water etc. A mixture of immiscible liquids is separated by using an apparatus called separating funnel.

Those liquids which do not mix with each other and form separate layer are called immiscible liquids. For Ex: Oil and water, Petrol and water etc. A mixture of immiscible liquids is separated by using an apparatus called separating funnel.

Evaporation is the process by which common salt is obtained from sea-water

We can use centrifuging method to separate the mixture of pure salt and rock salt. The rock salt are heavier than pure salt so during centrifuging process, the pure salt settles above whereas the rock salt settles down at the test tube.

The crystallisation method is used to purify solids. For example, to purify an impure sample of copper sulphate. To remove these impurities, the process of crystallisation is used. Crystallisation is a process that separates a pure solid in the form of its crystals from a solution.

Evaporation

Chromatography

Centrifugation is used in a washing machine to squeeze out water from wet clothes while drying.

Chromatography is used in forensic sciences to detect and identify trace amount of substances in the contents of bladder and stomach.

(a) fractional distillation

(b) separating funnel

(c) fractional distillation

(d) boiling points

(e) boiling points

(f) centrifugation

(g) magnet

The mixture of sugar and sand is taken in a beaker and water is added to it. The mixture is stirred to dissolve the sugar in water. The sand remains undissolved. The sugar solution containing sand is filtered by pouring over a filter paper kept in a funnel. Sand remains as a residue on the filter paper and sugar solution is obtained as a filtrate in a beaker kept below the funnel.

Salt is soluble in water whereas sand is insoluble in water. This difference in solubilities of salt and sand in water is used to separate them.

The mixture of salt and sand is taken in a beaker and water is added to it. The mixture is stirred to dissolve the salt in water. The sand remains undissolved. The salt solution containing sand is filtered by pouring over a filter paper kept in a funnel. Sand remains as a residue on the filter paper and salt solution is obtained as a filtrate in a beaker kept below the funnel.

Sugar is soluble in alcohols while salt is not. Simply mix the two in alcohol and filter the solution to get the salt. Then evaporate the alcohol sugar mixture and you will be left with the sugar.

The mixture of salt(sodium chloride) and sand is taken in a beaker and water is added to it. The mixture is stirred to dissolve the salt in water. The sand remains undissolved. The salt solution containing sand is filtered by pouring over a filter paper kept in a funnel. Sand remains as a residue on the filter paper and salt solution is obtained as a filtrate in a beaker kept below the funnel.

To separate the mixture of sand and potash alum . First mix it with water , then filteration. Alum can separated from water by crystallisation.

Carbon disulphide is a suitable solvent for sulphur. Sodium chloride remains undissolved and can be separated by filtration process.

It is separated by the process of sublimation. When the mixture of iodine and salt is heated, then iodine sublimates and salt is left.

We can separate the sublimating substance (Naphthalene / Anthracene / Camphor / Ammonium chloride/ Iodine) from the mixture of camphor and sand through the process of sublimation.

Spread the mixture of iron fillings and powdered carbon on a flat surface. Wrap the magnet in the paper towel. Use the magnet to remove the iron by pulling it across the surface of the mixture. The filings stick to the magnet while the sand and salt are left behind. Remove the paper towel from the magnet to collect the filings.

Spread the mixture of iron fillings and powdered carbon on a flat surface. Wrap the magnet in the paper towel. Use the magnet to remove the iron by pulling it across the surface of the mixture. The filings stick to the magnet while the sand and salt are left behind. Remove the paper towel from the magnet to collect the filings.

When a crane fitted with a powerful electromagnet is lowered on to the heap of waste materials, then the scrap iron objects get separated. The crane is then moved up and away to drop these scrap iron objects at a separate place.

If a mixture contains iron as one of the constituent, it can be separated by using horse shoe magnet. A mixture of iron and other impurities can be separated by using horse shoe magnet. This is because iron impurities are attracted by a magnet.

If a mixture contains iron as one of the constituent, it can be separated by using magnet. A mixture of iron pins and sand can be separated by using magnet. This is because iron pins are attracted by a magnet but sand is not attracted by a magnet.

Add water to the mixture of sand, salt and sulphur and stir. Salt will dissolve in water. Filter this solution and evaporate the filtrate to get salt. Add carbon disulphide to the residue containing a mixture of sulphur and sand. Sulphur will dissolve in carbon disulphide. Filter this solution.

The mixture containing sand is filtered by pouring over a filter paper kept in a funnel. Sand remains as a residue on the filter paper and mixture of water and kerosene is obtained as a filtrate in a beaker kept below the funnel.

When the mixture of water and kerosene is put in a separating funnel, it forms two layers. Water being heavier, forms the lower layer in the separating funnel whereas kerosene being lighter forms the upper layer. On opening the stop cock of separating funnel, the lower layer of water comes out first and collected in a beaker. When water layer has completely run off, then stop cock is closed. the kerosene is left behind in the separating funnel. It can be removed in a separate beaker by opening the stop cock again.

Sublimation is the process of transition of a substance from the solid to the gaseous state without passing through the liquid state. To separate mixtures that contain a sublimate with volatile component from a non-sublimate impurity, the sublimation process is used. Ammonium chloride changes directly from solid to gaseous state on heating. The gaseous form of ammonium chloride can be cooled easily to get a pure solid. Other examples of solids which sublime are camphor, naphthalene, anthracene, iodine, etc. The remaining components of the mixture are salt and sand. Salt is soluble in water and sand is a non-water soluble substance that can be separated by the process of filtration. The insoluble sand remains in the filter paper while the filtrate contains the dissolved salt. Evaporation technique is used to separate salt from the filtrate. Common salt does not decompose during evaporation. As the water evaporates, fewer and fewer water molecules are present to keep the salt particles apart. The salt therefore recrystallizes and can be collected.

Spread the camphor, salt and iron mixture on a flat surface. Wrap the magnet in the paper towel. Use the magnet to remove the iron by pulling it across the surface of the mixture. The filings stick to the magnet while the sand and salt are left behind. Remove the paper towel from the magnet to collect the filings. Mixture of camphor and common salt are heated. As camphor will sublime, leaving behind salt.

When the mixture of water, salt and groundnut oil is put in a separating funnel, it forms two layers. Water with salt being heavier, forms the lower layer in the separating funnel whereas oil being lighter forms the upper layer. On opening the stop cock of separating funnel, the lower layer of water comes out first and collected in a beaker. When water layer has completely run off, then stop cock is closed. the oil is left behind in the separating funnel. It can be removed in a separate beaker by opening the stop cock again.

The solution of common salt and water is taken in a china dish and heated gently by using a burner. The water present in salt solution will form water vapours and escape into atmosphere. When all the water present in the solution of common salt and water gets evaporated, then common salt is left behind in the china dish as a white solid.

Use the magnet to remove the iron- Spread the chalk powder, naphthalene and iron mixture on a flat surface. Wrap the magnet in the paper towel. Use the magnet to remove the iron by pulling it across the surface of the mixture. The filings stick to the magnet while the chalk and salt are left behind. Remove the paper towel from the magnet to collect the filings.

The mixture of chalk and naphthalene is separated by the process of sublimation. When the mixture of chalk and naphthalene is heated, then naphthalene sublimates and chalk is left.

Use the magnet to remove the iron- Spread the iodine, salt and iron mixture on a flat surface. Wrap the magnet in the paper towel. Use the magnet to remove the iron by pulling it across the surface of the mixture. The filings stick to the magnet while the chalk and salt are left behind. Remove the paper towel from the magnet to collect the filings.

The mixture of iodine and salt is separated by the process of sublimation. When the mixture of iodine and salt is heated, then iodine sublimates and salt is left.

Use the magnet to remove the iron- Spread the chalk powder, salt and iron mixture on a flat surface. Wrap the magnet in the paper towel. Use the magnet to remove the iron by pulling it across the surface of the mixture. The filings stick to the magnet while the chalk and salt are left behind. Remove the paper towel from the magnet to collect the filings.

To separate the chalk powder and salt-

(a) First, add water to the salt and chalk solution.

(b) Stir until the salt dissolves.

(c) The chalk will form a layer on top of the water, allowing you to scoop it out with a spoon.

(d) Then, let the water evaporate on a hot plate, which will cause the salt to be collected in the container.

Use the magnet to remove the iron- Spread the sand, salt and iron mixture on a flat surface. Wrap the magnet in the paper towel. Use the magnet to remove the iron by pulling it across the surface of the mixture. The filings stick to the magnet while the sand and salt are left behind. Remove the paper towel from the magnet to collect the filings.

Use warm water to dissolve the salt- Put the remaining salt and sand mixture into the glass of warm water, and stir until all the salt has dissolved. The sand remains undissolved and hence can be collected from bottom of the jar. The salt solution can undergo process of evaporation for the separation of salt.

Those liquids which do not mix with each other and form separate layer are called immiscible liquids. For Ex: Oil and water, Petrol and water etc. A mixture of immiscible liquids is separated by using an apparatus called separating funnel.

A mixture of two immiscible liquids (such as water and oil) can be separated by using a separating funnel.

When the mixture of water and mustard oil is put in a separating funnel, it forms two layers. Water being heavier, forms the lower layer in the separating funnel whereas oil being lighter forms the upper layer. On opening the stop cock of separating funnel, the lower layer of water comes out first and collected in a beaker. When water layer has completely run off, then stop cock is closed. the oil is left behind in the separating funnel. It can be removed in a separate beaker by opening the stop cock again.

A mixture of two immiscible liquids(such as water and oil) can be separated by using a separating funnel.

When the mixture of water and cooking oil is put in a separating funnel, it forms two layers. Water being heavier, forms the lower layer in the separating funnel whereas oil being lighter forms the upper layer. On opening the stop cock of separating funnel, the lower layer of water comes out first and collected in a beaker. When water layer has completely run off, then stop cock is closed. the oil is left behind in the separating funnel. It can be removed in a separate beaker by opening the stop cock again.

The separation of three immiscible liquids(mercury, oil and water) by a separating funnel depends on the differences in their densities. The mixture of three immiscible liquids is put in a separating funnel and allowed to stand for sometime. the mixture separates into three layers according to the densities of the liquid in it. The heavier or denser liquid forms the lower layer whereas the lighter liquids forms the middle and upper layers. On opening the stop cock of separating funnel, the lower layer of Mercury(heavier liquid) comes out first and collected in a beaker. When the lower layer of heavier liquid is completely run off, the stop cock is closed. The water in the medium layer is collected in a separate beaker by opening the stop cock again. Finally oil with lighter density than water and mercury will remain in funnel and can be connected in a separate jar.

A mixture of iron filing and sulphur powder can be separated by using magnet. This is because iron filling are attracted by a magnet but sulphur is not attracted by a magnet. In order to separate iron filing from sulphur powder, a horse-shoe magnet is moved over the surface of the mixture. The iron filings are attracted by the magnet, they cling to the poles of the magnet and get separated.

Answer- The process of centrifugation is used in dairies to separate cream from milk. The milk is put in a closed container in big centrifuge machine. When the centrifuge machine is switched on, the milk is rotated at a very high speed in its container. Due to this, the milk separates into cream and skimmed milk.

Procedure of purification of impure copper sulphate by crystallization-

1) Impure copper sulphate is dissolved in minimum amount of water.

2) The solution is filtered to remove insoluble impurities.

3) The clear solution is heated gently on a water bath till a concentrated solution or saturated solution is obtained.

4) Allow the hot ,saturated solution to cool slowly.

5) Crystals of pure copper sulphate are formed. Impurities remain dissolved in solution.

6) Separate the crystals of pure Copper sulphate by filtration and dry them.

The process of evaporation gives residue which may contain impurities. When there is requirement to obtain solid without impurity, crystallization method is preferred.

In general practice, impure solids are obtained by evaporation and are further purified by crystallization. Sugar crystal cannot be obtained by simple evaporation technique because sugar gets charred on heating to dryness. In such cases, crystallization technique is applied.

Chromatography is a method used to separate the different components in a liquid mixture. This method is based on the different properties of compounds in two phases: stationary and mobile phase.

Applications of chromatography

1) It is used to separate solution of coloured substances.

2) It is used in forensic sciences to detect and identify trace amount of substances in the contents of bladder and stomach.

3) It is used to separate small amount of products of chemical reaction.

A separating funnel is used for the separation of components of a mixture between two immiscible liquid phases. One phase is the aqueous phase and the other phase is an organic solvent. This separation is based on the differences in the densities of the liquids. The liquid having more density forms the lower layer and the liquid having less density forms the upper layer. Hence water and kerosene mixture can be separated by using a separating funnel whereas water and acetone are separated by the process of distillation.

There are many substances which are converted into gas from solid when heated, and converted from gas to solid when cooled without converting into liquid. Such substances are known as sublime. For example – ammonium chloride, naphthalene balls, camphor, etc. Therefore, mixture of one sublime and other substance can be separated using the method of sublimation.

The mixture of ammonium chloride and common salt can be separated out using the process of sublimation. For this, the mixture is heated in a China dish. The China dish is covered by an inverted funnel. Cotton is used for plugging the opening of the funnel. After heating, ammonium chloride is converted into vapour and gets deposited over the inner surface of funnel; due to cooling. This leaves the common salt in China dish. Ammonium chloride can be taken out by scratching from the inner wall of funnel.

The process of sublimation is used to separate that component of a solid-solid mixture which sublimes on heating. Hence the property of ammonium chloride to sublime has made this separations possible.

The solution of common salt and water is taken in a china dish and heated gently by using a burner. The water present in salt solution will form water vapours and escape into atmosphere. When all the water present in the solution of common salt and water gets evaporated, then common salt is left behind in the china dish as a white solid.

The process of evaporation is used on a large scale to obtain common salt from sea water. Evaporation is used for recovering dissolved solid substances from liquid mixtures but the liquid itself cannot be recovered by this method.

Process of water purification on a large scale at water works-

1). Sedimentation:

Water pumped from the source (river, lake or dam) is allowed to stand in large tanks, called settling tanks, for a few hours. Mud, sand and other suspended particles settle down. The addition of a small quantity of potash alum helps the suspended particles to settle down quickly. The solid that settles at the bottom of the tank is called sediment. That is why these tanks are also called sedimentation tanks. The water over the sediment layer is more or less clean.

2). Filtration:

The water from the sedimentation tank is filtered through layers of sand and gravel. Filtration is also done through activated charcoal, which affords better-quality water. Activated charcoal is a special type of charcoal made by heating ordinary charcoal in vacuum. This charcoal holds the impurities strongly.

3). Chlorination:

The filtered water is then treated with chlorine gas, which kills germs.

Process of adding chlorine (Cl) or hypochlorite to water ensures the killing of germs. This method is used to kill certain bacteria and other microbes in tap water as chlorine is highly toxic. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, typhoid etc.

Fractional distillation is the process of separating two or more miscible liquids by distillation. The distillate being collected in fractions boiling at different temperatures. The separation of two liquids by fractional distillation depends on the differences in their boiling points. A simple Fractionating column is a long vertical glass tube filled with glass beads. It can be regarded as an arrangement for providing different temperature zones inside it, the highest temperature being at the bottom of the column and lowest temperature near its top. The Fractionating column is fitted in the neck of the distillation flask containing the mixture of liquids to be separated.

The boiling point of alcohol is 78°C and boiling point of water is 100°C therefore a mixture of alcohol and water can be separated by fractional distillation. The alcohol with boiling point 78°C will distil first and then water with boiling point 100°C will distil later. Fractional distillation separates the various liquids according to their boiling point, the more volatile liquid (having lower boiling point) distils first and the less volatile liquid (having higher boiling point) distils later.

Air comprises of nitrogen, oxygen, carbon dioxide and argon as major components. Since air is the cheapest source of these gases, thus these are extracted from air at large scale. After liquefaction of air by repeated compression and cooling; nitrogen, oxygen, carbon dioxide and argon are extracted using fractional distillation. Liquid nitrogen has boiling point equal to - 196⁰C and thus turns into gas first and separated from air. The boiling point of argon is - 186⁰C, therefore it is extracted after argon. The boiling point of oxygen is - 183⁰C, thus it is collected after the extraction of argon. Carbon dioxide turns into solid at a temperature of - 97⁰C, therefore, it is removed while air is put under liquefaction.

A mixture of two immiscible liquids can be separated by using a separating funnel such as oil and water.

Both sugar and sulphur are insoluble in water,so water can not be used as a solvent to separate them. However sulphur is soluble in carbon disulpide whereas sand is insoluble in carbon disulpide.

Sulphur is soluble in a solvent called carbon disulphide. Carbon is not soluble in carbon disulphide.

The mixture of different colors/dyes/inks are separated by the process of chromatography.

Impure copper sulphate can be purified by the method of crystallisation.

Process of adding chlorine (Cl) or hypochlorite to water ensures the killing of germs. This method is used to kill certain bacteria and other microbes in tap water as chlorine is highly toxic.

Centrifugation is a method of separating the suspended particles of a substance from a liquid in which the mixture is rotated at a high speed in a centrifuge.

The process of sublimation is used to separate that component of a solid-solid mixture which sublimes on heating. Naphthalene sublimes on heating.

hydrogen cannot be separated from air by the process of fractional distillation

Liquid nitrogen has boiling point equal to - 190⁰C and thus turns into gas first and separated from air. The boiling point of argon is - 186⁰C, therefore it is extracted after nitrogen. The boiling point of oxygen is - 183⁰C, thus it is collected after the extraction of argon.

The boiling point of argon is - 186⁰C, therefore it is extracted after nitrogen.

(b), Distillation is a method used for the separation of components of a mixture containing two miscible liquids that boil without decomposition and have sufficient difference in their boiling points.

(d), The process of cooling a hot, concentrated solution of a substance to obtain crystals is called crystallisation. It is used for obtaining a pure solid substance from impure sample.

Silica does not undergo sublimation.

Chromium does not show magnetic properties.

(a) Y; It has the highest boiling point of, -183C

(b) Z; It has the lowest boiling point of, -196C

(c) X; It has a boiling point of, -186C, which is lower than that of Y but higher than that of Z

(d) X is liquid argon; Y is liquid oxygen; Z is liquid nitrogen

(a) Fractional distillation is used for the separation of a mixture of two or more miscible liquids for which the difference in boiling points

(b) A separating funnel is used for the separation of components of a mixture between two immiscible liquid phases. One phase is the aqueous phase and the other phase is an organic solvent. This separation is based on the differences in the densities of the liquids.

(c) (i) Alcohol (ii) Water (iii) Oil

(a) P is sand; Q is common salt; R is iron filings; S is ammonium chloride

(b) First separate R (iron filings) by using a magnet to attract them. Then separate S (ammonium chloride) by sublimation. Shake P (sand) and Q (common salt) with water and filter. Sand is obtained as residue. Evaporate filtrate to dryness to obtain common salt.

(a) Alcohol

(b) Iodine

(c) The process of sublimation is used to separate those substances from a mixture which sublime oh heating. Iodine has the property to sublime.

(d) Distillation is a method used for the separation of components of a mixture containing two miscible liquids that boil without decomposition and have sufficient difference in their boiling points.

(e) Evaporation is used to separate a solid substance that has dissolved in water.

(a) (i) Sulphur (ii) Carbon disulphide

(b)(i) Copper sulphate (ii) Water

(c) Vegetable oil

(d) Filter the mixture of A, B and C. C(oil)being liquid will be obtained as a filtrate. Residue consists of A (sulphur) and B (copper sulphate). Add water, shake and filter. A (sulphur) is obtained as residue. Evaporate filtrate to obtain B (copper sulphate).

Ice, iron, hydrochloric acid, calcium oxide and mercury are the pure substances whereas milk, brick, wood and air are impure substances.

Elements- Substances that are made of only one element are called elements, He, Cl, Co.

Compounds- Substances that are made of one or more elements by chemical combination are called compounds. H₂O and CO.

Elements: Iron, Sodium, Sulphur and carbon.

Compounds: Iron sulphide, chalk, washing soda and urea.

Chemical formula of Sugar is C₁₂H₂₂O₁₁. It contains C, H and O Elements Chemical formula of Common salt is sodium chloride, NaCl. It contains Na and Cl elements.

A sample of matter containing only one substance is called a pure substance. In other words all constituents of the substance are same in their chemical nature.
A pure substance contains only one kind of atoms or molecules. It is perfectly homogenous. The two examples are Hydrogen and Sodium.

The two types of pure substances are-

(i) Elements- Hydrogen

(ii) Compounds- Water

Mixture is the other name to describe impure substances. For example- Milk and Air.

Air is a homogeneous mixture of a number of gases. It's two main constituents of gases are oxygen (21%) and Nitrogen (78%)

The constituent particles of homogenous mixture cannot be separated using centrifugation or decantation.

Elements: Mercury, iron, diamond, nitrogen, Graphite, hydrogen, oxygen and Chlorine.

Solid elements- Sodium and Copper.

Liquid elements- Mercury and bromine

Gaseous elements- Hydrogen and oxygen.

Hydrogen and oxygen are made up of same kind of atom hence these are considered as elements whereas water is made by the combination of different kinds of atoms such as hydrogen and oxygen, hence it is called as a compound and not an element.

Elements can be classified as metals, non-metals and metalloids.

Examples of metals- Copper and Aluminium.

Non-metals - Hydrogen, Oxygen.

Metalloids - Boron, Silicon.

Two physical properties that differentiate metals from non-metals are-

(i) Metals, except mercury&gallium are solids at room temperature while non-metals, except bromine are solidsorgases at room temperature.

(ii) Metals are malleable and ductile while non-metals are non-malleable & non-ductile

(iii) Metals are lustrous while non-metals, except diamond & graphite which are allotropes of carbon as well as iodine, are non-lustrous.

(i) Metals are malleable i.e. they have ability to be flattened into thin sheets by hammering or rolling such as aluminum whereas non-metals are non-malleable.

(ii) Metals are ductile stretched into wires such as copper whereas non-metals are non-ductile.

(iii)Metals are good conductors of heat & electricity. Exception: Lead & mercury are poor conductors of heat. Non-metals are poor conductors of heat and electricity. Exception: Graphite conducts electricity.

Two properties that aluminium is a metal:

(i) Aluminium is malleable i.e. it has ability to be flattened into thin sheets by hammering or rolling.

(ii) Aluminium is good conductor of heat and electricity.

(a) Copper metal is ductile in nature, i.e. it can be drawn into wires. Hence copper metal is used for making electric wires.

(b) Non-metals are poor conductors of heat and electricity. Graphite is an exception in non-metals that conducts electricity. Hence, graphite is used for making electrode in a dry cell

In order to distinguish pure water from impure solutions(mixture), we should evaporate them separately. The liquid which evaporates completely, leaving no residue, is a pure compound. On the other hand, the liquid which leaves behind a residue in evaporation, is a solution or mixture.

Sea-water and Soda-water are the solutions from following mixtures.

Air is considered a mixture because of the following reasons:

(i) Air can be separated into its constituents like oxygen, nitrogen, etc., by the physical process of fractional distillation.

(ii) Air shows the properties of all the gases present in it. For example, oxygen supports combustion and air also supports combustion; carbondioide turns lime water milky and air also turns lime water milky, though very, very slowly.

(iii) Air has a variable composition because air at different places contains different amounts of the various gases.

Water is considered a compound because of the following reasons-

(i) Water cannot be separate into its constituents, hydrogen and oxygen, by the physical methods.

(ii) The properties of water are entirely different from those of its constituents, hydrogen and oxygen. For example, water is a liquid whereas hydrogen and oxygen are gases; water does not burn whereas hydrogen burns; water does not support combustion whereas oxygen supports combustion.

A compound is a substance made up of two or more elements chemically combined in a fixed proportion by weight.

Evidence to show that sodium chloride is a compound-

(i) Common salt, Sodium chloride is a compound made up of two elements, sodium and chlorine.

(ii) If a magnet is put in the sodium chloride compound, sodium does not get separated from chloride. A compound cannot be separated into components by physical methods.

A mixture is a substance which consists of two or more elements or compounds not chemically combined together.

Two evidences to show that sugar solution is a mixture-

(i) A mixture of sugar in water is a homogeneous mixture because all the parts of sugar solution have the same sugar water composition and appears to be equally sweet.

(ii) There is no visible boundry of separation between sugar and water particles in a sugar solution.

Brass is a mixture and not a compound because in compound the elements should be in definite proportions and the elements are chemically bonded to each other.
Whereas in brass the two elements Zn & Cu are not in definite proportions (they can mix in any ratio) & there is no chemical bonding between them.

COMPOUND
1). It is a pure substance.
2). It cannot be separated by physical method.
3). Element loose their properties in a compound.
4). Its composition is fixed throughout its mass.
5). It has fixed melting point.
MIXTURE
1). It is an impure substance.
2). It can be separate by physical method.
3). Substances forming mixture retain their properties.
4). It has no fixed composition.
5). It has no sharp melting point.

(i) A mixture of salt in water is a homogeneous mixture because all the parts of salt solution have the same salt water composition and appears to be equally salty.

(ii) There is no visible boundary of separation between salt and water particles in a salt solution.

there is a visible boundary of separation between salt and water particles in a salt solution.

(i) In a compound, two or more elements are chemically bound together. However, in a solution, there are few substances that do not chemically bound together as compounds do (molecules or compounds in a solution may have weak interactions between them, but it is different from the chemical binding of elements in compounds).

(ii) In a compound, elements are present in defined ratio, but in a solution, the components in it have not necessarily to be present in definite amounts.

(iii) The components in a solution can be separated in physical methods, but in a compound, this cannot be done. They may be separated by chemical means.

(iv) Compared to compounds, solutions have two phases called solutes and the solvent.

(a) Iodine is lustrous in nature.

(b) Oxygen is necessary for combustion.

(c) Carbon is the non-metal whose allotrope Graphite, is a good conductor of electricity.

(d) Sulphur also shows allotropy.

(e) Carbon is the element to form largest number of compounds.

(a) Sodium is a soft metal which can be easily cut with a knife.

(b) Mercury can form amalgams.

(c) Mercury has no fixed shape as it is a liquid.

(d) Sodium has a low melting point.

(e) Gold is yellow in colour.

Chlorine gas, Aluminium foil, Graphite, Sulphur powder and diamond are elements.

Air is needed for the combustion (or burning) of fuels. Which component of air actually supports combustion?

Air shows the properties of all the gases present in it. Oxygen present in it supports combustion and hence air is needed for combustion.

Homogeneous mixture- Alcohol and water mixture, Sugar and water mixture,

Heterogeneous mixture- Chalk and water mixture,

(a) (i) Elements- An element is a substance which cannot be split up into two or more simpler substances by the usual chemical methods of applying heat, light or electric energy. Sodium and Hydrogen are two elements.

(ii) Compounds- A compound is a substance made up of two or more elements chemically combined in a fixed proportion by weight. Water and sodium chloride are two compounds.

(v) Mixtures- A mixture is a substance which consists of two or more elements or compounds not chemically combined together. Air and Gun powder are two mixtures.

Elements - Gold, Graphite, Diamond,

Compounds - Common salt, Chalk, Marble

Mixtures - Air, Brass, Petroleum, Sea water, Sand.

(i) Metal - A metal is a material (an element, compound, or alloy) that has physical properties: hard, opaque, shiny, and conductivities. Metals are generally malleable, fusible and ductile. Metals are good conductors of heat & electricity.

Example: Aluminium, Copper, Iron, etc.

(ii) Non-Metal- Non-metals are opposite in properties of the metals. The non-metals are brittle, not malleable or ductile, poor conductors of both heat and electricity.

Example: Oxygen, Fluorine, Neon, Chlorine, etc.

(iii) Metalloids - Metalloids are a type of semi-metals, that sometimes behave as a metal and sometimes behave as a non-metal.

Example: Silicon, Germanium etc.

A mixture is a substance which consists of two or more elements or compounds not chemically combined together. Air and Gun powder are two mixtures.

(i) A homogeneous mixture has a uniform composition throughout its mass. It has no visible boundaries of separation between the various constituents. Mixture of sugar and water and mixture of alcohol and water are two examples of homogeneous mixtures.

(ii) A heterogeneous mixture does not have a uniform composition throughout its mass. It has visible boundaries of separation between the various constituents. A mixture of petrol and water and mixture of chalk in water are two examples of heterogeneous mixtures.

All the homogeneous mixtures are also called Solutions.

On the basis of chemical constitution, all the matter can be classified into three groups:

(i) Elements- An element is a substance which cannot be split up into two or more simpler substances by the usual chemical methods of applying heat, light or electric energy. Sodium and Hydrogen are two elements.

(ii) Compounds- A compound is a substance made up of two or more elements chemically combined in a fixed proportion by weight. Water and sodium chloride are two compounds.

(iii) Mixtures- A mixture is a substance which consists of two or more elements or compounds not chemically combined together. Air and Gun powder are two mixtures.

No Answer

Silica is

CO, carbon monoxide and NO, nitrogen oxide are compounds.

Germanium is neither a good conductor of electricity nor an insulator.

Alcohol is a compound made up of carbon, hydrogen and oxygen.

chemical formula of baking soda is NaHCO3 and chemical formula of soda ash is Na2CO3 .

Malleability and ductility are the properties of metals.

Some element have intermediate properties of the metals and non-metals. The elements which exhibit the properties of metals as well as non-metals, are called metalloids. Example Boron, Silicon, Germanium etc.

Bromine is a non metal which exists in the liquid state whereas mercury is a metal which exists in the liquid state.

the exothermic reaction of two elements, iron and sulfur, to form the compound, iron sulfide.

ductility is the property of metals in which they can be drawn into wires.

Milk is the mixture of fat, water, and other constituents.

A pure substance contains only one kind of atoms or molecules. It has definite composition which does not vary with time.

ice and air are homogeneous in nature.

No Answer

Air does not have a fixed melting point/boiling point.

Steam does not belong to the set. This is because all others are elements whereas steam is a compound.

(a) Substance B is a mixture (Fe + S).

(b) Substance C is Compound (Iron sulphide, FeS).

(c) (i) Hydrogen sulphide, H₂S

(ii) Hydrogen, H₂

(d) Hydrogen sulphide has smell of rotten eggs.

(a) Mixture; Salt Solution (b) Element; Sulphur

(c) Compound; Water

(d) Formations of Z (which is a compound)

(e) Metals, Non-metals and Metalloids

(a) Elements

(b) Substances Q are Non-metals; Two examples are Carbon and Sulphur.

(c) Substances R are Metals; Two examples are Sodium and Aluminium

(d) Substances S are Metalloids; Boron and

Silicon (e) Substances R are malleable and ductile as they are metals.

(a) B; Mercury

(b) C; Salt solution

(c) A; Alcohol

(d) Sodium chloride (Common salt)

(e) Water

(a) A solution has the smallest particles. The size of the solute particles in a true solution is 10-8 cm.

(b) A suspension has the largest particles. The size of the particles in suspension is larger than 10-5 cm.

Solution is the name of the clear liquid formed when a solid dissolves in a liquid.

A soap solution will scatter light passing through it as it is a colloid.

Though colloids appear to be homogeneous to us but actually they are found to be heterogeneous when observed under a high power microscope.

The most common way of expressing the concentration of a solution is the percentage method. The percentage method refers to the ‘percentage of solute’ present in the solution.

To get 15% of salt solution you need 15g of salt and will add 85g of water so total
solution count = solute + solvent = 15g + 85g = 100g.

To get 12% of alcohol solution you need 12ml of alcohol and will add 88g of water so total
solution count = solute +solvent = 12g +88g =100g.

(a) 5 g of sugar is dissolved in 95 g of water.

(a) 15 ml alcohol and 85 ml water.

Concentration = Mass of solute/Mass of solution × 100

Mass of solute = 2.5g

Mass of solution = 50g

Concentration of a solution = 2.5/ 50 * 100% = 4.7% (w/w)

Concentration=Mass of solute/Mass of solution×100

Mass of solute = 16g

Mass of solution = 120g

Concentration of a solution = 16 / 120 * 100% = 13.3% (w/w)

Volume of the solute (salt) = 5.6 ml
Volume of the solvent (water) = 75 ml
Volume of the solution = Volume of the solute + volume of the solvent
= 5.6 + 75 = 80.6ml
Volume percentage of solution = Volume of solute /Volume of solvent x 100%

= 5.6/80.6 x 100 = 6.9%

Concentration= Volume of solute/Volume of solution×100

Volume of solute = 25ml

Volume of solution =150ml

Concentration of a solution= 25/ 150 * 100% = 16.6% (v/v)

When the temperature of a saturated sugar solution is increased, it become super saturated.

Unsaturated solution contains less solute at a given temperature and pressure.

When water is cooled, then water solidifies to form ice. This is called freezing of water. The freezing of water to form ice is a physical change.

During electrolysis, when water forms hydrogen and oxygen, it undergoes chemical change.

(a) True (b) False

Colloid is the term which includes aerosol, emulsion and sol.

Soap solution

(a) colloidal; true

(a) The substance which is dissolved in a liquid to make a solution is called solute.

(b) The liquid in which solute is dissolved is known as solvent.

The difference in the properties of a true solution and a colloid is due to the different size of their solute particles. The solute particles in a true solution are very small whereas the solute particles in a colloid are slightly bigger.

True solutions- Salt solution, Sugar solution.

Colloidal- Ink, Starch solution, Blood.

We can distinguish between colloids and true solutions by using Tindall effect. If the solution scatters a beam of light passing through it and renders its path visible, will be a colloid.

When a beam of light is passed through a colloidal solution such as a soap solution, it scatters a beam of light passing through it and renders its path visible.

We can distinguish between colloids and true solutions by using Tindall effect. If the solution scatters a beam of light passing through it and renders its path visible, will be a colloid.

The solution which does not scatter a beam of light passing through it and does not render its path visible, will be a true solution.

it is due to the small size of their solute particles that a colloid easily pass through the pores of a filter paper whereas it is because of the bigger size of the solute particles of a suspension that they cannot pass through the pores of a filter paper and are retained on the filter paper in the form of a residue. Only the solvent of a suspension passes through the filter paper.

The size of solid particles in a suspension is quite large. The size of particles in a suspension is larger than 10-5 cm. In a suspension, the particles do not dissolve in the liquid. The particles of a suspension are big enough to be seen with a naked eye.

(b) Milk will show tyndall effect, it scatters a beam of light passing through it and renders its path visible as it is a colloid. The scattering of light by colloidal particles is called tyndall effect.

Solid - solid solution – Solution of two or more solids are generally known as solid-solid solution. For example – alloys.

Solid – Liquid solution – Solution of solid and liquid is called solid-liquid solution. For example - solution of salt and water.

Liquid – liquid solution – Solution of two miscible liquids are called liquid-liquid solution, such as solution of water and acetic acid. The solution of acetic acid in water is known as vinegar.

Gas - liquid solution – Solution of gas into liquid is called gas-liquid solution. For example – Soft drink.

Gas-gas solution – Solution of two or more gas is called gas-gas solution. For example – air, which is the solution of many gases, such as hydrogen, oxygen, carbon dioxide, etc.

Solutions- Brine, Soda water.

Suspensions- Muddy river water, Chalk water mixture, Milk of magnesia, Smoke in air.

Colloids- Milk, Ink, Blood, shaving cream.

(a) Colloidal solution is called sol when liquid is dispersing medium and solid is dispersed phase. For example – blood, ink, paint, etc.

(b) When particles of solid or liquid dispersed in gaseous medium, the mixture is known as Aerosol. For example – cloud, smog, smoke etc.

(c) Colloidal solution is called emulsion, when dispersing medium and dispersed phase both are liquid. For example – milk, butter, face cream, etc.

(d) Mixtures are called foam when liquid is present as dispersing medium and gas is dispersed medium. For example – shaving cream, soap bubbles, etc.

The concentration of a solution is the amount of solute present in a given quantity of the solution.

(i) When saturated solution is heated, it will become unsaturated

(iii) When saturated solution is cooled, some of the dissolved solute will separate and crystallizes.

21.5g of NaCl dissolves in 60g of water

So amount of NaCl which gets dissolved in 100gm of water=21.5x100/60=35.8

The solubility of sodium chloride is 35.8 at 25C.

9.72g of KCl dissolves in 30g of water

So amount of KCl which gets dissolved in 100gm of water=9.72x100/30=32.4

The solubility of potassium chloride is 32.4 at 70C.

(i) Cooking of food- Chemical change

(ii) Boiling of water- physical change

(iii) Cutting of trees- Physical change

(iv) Dissolving salt in water- Physical change

(v) Digestion of food- Chemical change

(vi) Melting of ice- physical change.

(a) Burning of a magnesium wire-Chemical change

(b) Freezing of water- Physical change

(c) Rusting of iron- Chemical change

(d) Glowing of an electric bulb- Physical change

(i) Formation of curd from milk-Chemical change

(ii) Condensation of steam- Physical change

(iii) Growth of a plant- Chemical change

(iv) Breaking of a glass tumbler- physical change

Physical changes- Sublimation of a solid, Formation of clouds, Making a fruit salad from raw fruits, Dissolving carbon dioxide in water.

Chemical changes- Decomposition of water into hydrogen and oxygen by passing electric current

Physical changes- Melting of candle wax, Mixing of iron filings and sand, Breaking a piece of chalk, Cutting a piece of paper

Chemical changes- Burning of candle wax, Burning of wood, Burning a piece of paper.

Sea water is the mixture of many salts, water and other many impurities. Apart from these many gases are also dissolved in sea water. Because of salt and some other bigger size of impurities sea water is classified as heterogeneous mixture. Because of mixture of several gases in sea water it is also classified as homogeneous mixture.

Sugar solution, salt solution, Copper sulphate solution.

Physical changes : Those changes in which no new substances are formed, are called physical changes. In a physical change the substances involved do not change their identity. They can be easily returned to their original form by some physical process. The changes in physical state, size and shape of a substances are called physical changes. Example: When ice is heated it melts to form water, Boiling of water, condensation of steam

Those changes in which new substances are formed, are called chemical changes. A chemical change is also called a chemical reaction. In a chemical change, the substances involved, change their identity . They get converted into entirely new substances. The new substances usually cannot be returned to their original form. This means that chemical changes are usually irreversible.

Burning of candle and burning of hydrogen in oxygen to form water.

Physical Change Chemical Change

(1). New substances are not formed 1. New substances are formed

(2). A physical change is a temporary change 2. A chemical change is a permanent change

(3). A physical change is easily reversible 3. A chemical change is usually irrerversible.

(4). The mass of substances does not alter in a 4. The mass of substance does alter in a physical change. chemical change

(i) a glass bottle breaking- Physical change

(ii) coal burning in air- Chemical change

(iii) making a cake- Chemical change

(iv) wool being knitted into a sweater- Physical change

Solubility is the amount of solute in a saturated solution at a given temperature. In other words, maximum capacity to dissolve a solute in a solution at a given temperature is called solubility. Different solvents can dissolve different amount of solute. This means different solvents have different solubility.

No Answer

Solubility increases with increase in temperature

A solution is a homogeneous mixture of two or more substances. E.g. Salt solution, Sugar solution.

A suspension is a heterogeneous mixture in which the small particles of a solid are spread throughout a liquid without dissolving in it. E.g. Chalk water mixture, muddy water.

A colloid is a kind of solution in which the size of solute particles is bigger than that of a true solution but smaller than that of a suspension. E.g. milk and ink.

Saturated Solution: When a solution cannot dissolve more solute at a given temperature, the point is called saturation point of the solution and solution is called saturated solution. This means, no more solute can be dissolved in a saturated solution at a given temperature.

Unsaturated Solution: Solution in which more solution can dissolved at a given temperature, is called unsaturated solution.

Example to test whether a given solution is saturated or not

At 25°C, 55 g of common salt dissolves in 100g of water. However, if more of common salt is added to the above solution, it just does not dissolve. In such a situation, the solution of common salt containing 55 gm of salt in 100 gm of water, is a saturated solution at 25°C

At 25°C, 55 g of common salt dissolves in 100g of water. However, if more of common salt is added to the above solution, it just does not dissolve. In such a situation, the solution of common salt containing 55 gm of salt in 100 gm of water, is a saturated solution at 25°C

Bread is an example of solid foam.

Shaving cream is , whereas face cream, milk and butter are emulsions.

Sugar solution does not show tyndall effect as it is a true solution.

Chalk powder and water mixture is a colloidal solution which exhibits tyndall effect.

Milk of magnesia is a suspension as it is a heterogeneous mixture.

(b)

sublimation of naphthalene is not a chemical change as it is reversible.

(a)

Milk of magnesia is called suspension as it is a heterogeneous mixture.

Solution of two or more solids are generally known as solid-solid solution. For example – alloys. Alloy is a homogeneous mixture of two or more metals and non metals or two metals or two non-metals.

(c)

A mixture of sulphur and carbon disulphide is homogeneous solution and does not show Tyndall effect.

(d)

(c)

(a)