Science Do as directed; [Che-1 M]

Dispersed phase is gas and dispersing medium is solid.
Other eg: rubber or sponge.

Colloid: A colloid is a heterogeneous mixture whose particles are not as small as solution but they are so small that cannot be seen by naked eye. When a beam of light is passed through a colloid then the path of the light becomes visible. For example milk, smoke etc.
Properties of a colloid:

• A colloid is a heterogeneous mixture.
• The size of particles of a colloid is too small to be individually seen by naked eyes. 
• Colloids are big enough to scatter a beam of light passing through it and make its path visible. 
• They do not settle down when left undisturbed, that is, a colloid is quite stable.
• They cannot be separated from the mixture by the process of filtration. But, a special technique of separation known as centrifugation can be used to separate the colloidal particles.

Allotrope of carbon forms good conductor of electricity. That allotrope is graphite.

Non-metals show brittleness.

Centrifugation.

Chromatography.

(b) milk and (d) starch solution show Tyndall effect because they are colloidal solution.
Whereas (a) salt solution and (c) copper sulphate solution are true solution. Their particle size is too small to scatter light. So they do not show Tyndall effect.

(b) milk and (d) starch solution show Tyndall effect because they are colloidal solution.
Whereas (a) salt solution and (c) copper sulphate solution are true solution. Their particle size is too small to scatter light. So they do not show Tyndall effect.

Tyndall effect is shown by colloidal solution. Here milk and starch solution are colloids therefore milk and starch solution will show Tyndall effect.

Elements: Mercury, Iron, Diamond, Nitrogen, Graphite, Hydrogen, Oxygen and chlorine.

Soap solution.

Sugar solution, Salt solution, copper sulphate solution and ammonium chloride solution do not show Tyndall effect.

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

Ice, iron, hydrochloric acid, calcium oxide and mercury are the pure substances.

Chlorine gas, Aluminium foil, Iodine vapour, Graphite, Sulphur powder, Diamond are not compounds.

For the purification of solids crystalisation process is commonly used up:
Crystallization is the (natural or artificial) process of formation of solid crystals precipitating from a solution, melt or more rarely deposited directly from a gas.

Sublimation.

This is a experiment of separating dye from ink: Fill half a beaker with water and put a watch glass on the mouth of the beaker. Put few drops of ink on the watch glass. Now start heating the solution or mixture. after that the water evaporate continue heating till there is no further change in the watch glass. When the water is completely evaporated from the watch glass Dye is left in the watch glass.

Electromagnet.

Metalloids.

The pigments of natural colours can be separated by Chromatography.

A colloid is typically a two phase system consisting of a continuous phase (the dispersion medium) and dispersed phase (the particles or emulsion droplets). The particle size of the dispersed phase typically ranges from 1 nanometer to 1 micrometer.

Other name for homogeneous mixtures is SOLUTIONS.

Mixture is another name for impure substances.
Examples: Milk and sea-water.

Percentage method.

Filtration.

Hydrogen sulphide or H₂S has a smell of rotten eggs. H₂ or hydrogen does not have any odor.

In the true solution the sizes of the particles are very low and is approximately less than 1nm, which cannot be seen by naked eyes.

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

This means that metals make a ringing sound when we strike them.

This means that metals can be drawn into thin sheets and can also be drawn into wires.

This means that metals are shiny in nature.

This means that metals make a ringing sound when we strike them.

If it is a super Saturated solution sugar particles will start crystallising.

When a beam of light is passed through a colloidal solution, then scattering of light is observed. This is known as the Tyndall effect. This scattering of light illuminates the path of the beam in the colloidal solution.

The colloidal particles are charged and carry either a positive or negative charge. The dispersion medium carries an equal and opposite charge. This makes the whole system neutral. Under the influence of an electric current, the colloidal particles move towards the oppositely charged electrode. When they come in contact with the electrode, they lose their charge and coagulate.

When the temperature of a saturated sugar solution is increased, it becomes unsaturated.

This statement means that 100g of water can dissolve a maximum of 20.7g of copper sulphate at 20°C.

Difference in the densities of oil and water enable their separation by a separating funnel.

Difference in their boiling point.

The difference in the solubility of salt and sand in water is used to separate them from their mixture.

Three general classes of matter are elements, compounds and mixtures.

1. Element: Hydrogen.
   
2. Compound: Sodium chloride.
   
3. Mixtures: Salt solution.
   

A pure substance is one which is made up of only one kind of atoms or molecules.
Examples: Oxygen and sugar.

Alloys are homogenous mixtures because they have a uniform composition throughout.

Pure substance: Water, salt, sugar.
Mixture: Saltwater, soil, wood, air, cold drink, rubber, sponge, fog, milk, butter, clothes, food.

Crystallization is a process that separates a pure solid in the form of its crystals from a solution.
Crystallization is better than evaporation because during
Evaporation:

1. Some solids decompose or some, like sugar may get charred on heating to dryness.
2. Some impurities may remain dissolved in the solution even after.

The given statement best describes a compound.

Sublimation. Ammonium chloride is a sublimating compound and can be separated from the mixture through sublimation.