How does the meaning of pure substance different for a common man that to a chemist? Explain.

List the points of differences between homogeneous and heterogeneous mixtures.

Define the following terms:
(i) True solution
(ii) Solute
(iii) Solvent      
(iv) Solubility.

What are colloidal solutions? Give examples.

Explain dispersed phase and dispersion medium in relation to colloidal solution.

What is chromatography? State its applications.

(a) Name the techniques used for separation of those solutes that dissolve in the same solvent.
(b) give any two applications of this technique.

What are the advantages and disadvantages of crystallisation over evaporation?

Define physical and chemical changes.

(a) name the separation techniques which you will apply the separation of the following mixtures:
(i) Small piece of metal in the engine oil of a car
(ii) Fine mud particles suspended in water 
(iii) Oil from water.
(iv) Sodium chloride from its solution in water.
(v) Camphor from salt.
(vi) Wheat grains from husk.
(b) Classify the following as a chemical or physical change:
(i) Water boils to form steam.
(ii) Burning of paper.
(iii) An almirah gets rusted.
(iv) Making a fruit salad with raw fruits.

Why is water considered as compound?

Mixtures can be separated into their constituents by using physical methods. The technique used depends on the different properties of the constituents, e.g., different states, solubility, boiling, and melting points. The most common separation techniques are
(i) Chromatography,
(ii) Distillation,
(iii) Evaporation,
(iv) Fractional distillation,
(v) Filtration.
Give example mixtures one in each case that can be separated explaining the principle involved.

A mixture is a combination of two or more substances that are not chemically united and do not exist in fixed proportions to each other.It can be physically separated into pure compounds or elements.Suppose you have a mixture of water, oil, iron filings and sulphur.
What steps you will take to separate the constituents of this mixture which are compounds and which are elements.

A class was divided into four groups - A, B, C, and D.Group A was given a few crystals of sodium salt, group B 100g of sodium nitrate, group C, a few particles of wheat flour, and group D, fine particles of mud. Each group was asked to add their samples in 50g water and stir properly using a glass rod. The mixtures were allowed to stand undisturbed for some time. The mixtures were then filtered.
Answer the following questions giving reasons.
(a) Which group/s will get the residue left on the filter paper?
(b) Which group/s will get a filtrate that scatters a beam of light or show the Tyndal effect?
(c) Which group/s will get a clear liquid, i.e., water back on filtration?
(d) Which group got a suspension?
(e) Which group got a clear solution?

Write would you observe when
(i) A saturated solution of potassium chloride prepared at 608\(°\)C is allowed to cool at room temperature.
(ii) An aqueous solution of sugar is heated to dryness.
(iii) A mixture of iron filings and sulphur powder is heated strongly.