What are heterogeneous mixtures? Give examples.

Sol. Mixtures which have physically distinct parts and have non-uniform compositions throughout the sample are called heterogeneous mixtures.
As for example, mixtures sodium chloride and iron filings, salt and sulphur and oil and water etc.
** Some other important questions with answers -
Chapter-2
"IS MATTER AROUND US PURE" of NCERT Science textbook of class IX

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1. What are diferent things of this universe made up of?
Ans. Matter
2. What are matters made up of?
Ans. Matters can be made up of elements, compounds or mixtures.
Facts to be known : Molecules of elements are made up of one type of atoms. As for example He, Ne, Ar, O2, O3, H2, Cl2 etc. are elements.
Molecules of compounds are made up of more than one type of atoms. As for example HCl, NaCl, H2O, Na2CO3, NaHCO3 etc. are compounds.
Mixtures have different types of matters which may be elements or compounds or both.
As for example air is a mixture of both elements like O2, H2, N2 ctc. and compounds like CO, CO2, H2O, SO2, NO, NO2 etc.
3. Is milk pure according to scientists?
Ans. No. According to scientist, milk is not pure. Instead, it is a mixture of water, fat, proteins etc.
4. What is meant by pure substance? Give example.
Ans. A substance is pure when all the constituent particles of the substance are the same in their chemical nature.
Example - O2, H2O, NaCl etc.
(Note : All elements and compounds are considered to be pure.)
Facts to be known : 
       1. Most of the matters around us exists as mixtures of two or pure components, for example, sea water, minerals, soil etc.
2. Pure substances cannot be separated into other kinds of matter by any physical process.
4. Name a physical process through dissolved sodium chloride can be separated from water?
Ans. Evaporation
5. Give reason - "sugar is a pure substance".
Ans. Sugar is a pure substance, because it consists of one kind of pure matter and composition is the same throughout.
6. What are homogeneous mixtures? Give examples.
Ans. Mixtures which have uniform composition throughout are called homogeneous mixtures.
As for example, salt in water, sugar in water etc.
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7. What are heterogeneous mixtures? Give examples.
Sol. Mixtures which have physically distinct parts and have non-uniform compositions throughout the sample are called heterogeneous mixtures.
As for example, mixtures sodium chloride and iron filings, salt and sulphur and oil and water etc.
8. List the points of differences between homogeneous and heterogeneous mixtures.
Ans. Homogenous Mixtures Heterogenous Mixtures
i. A mixture in which different constituents are mixed properly. i. A mixture in which different constituents are not mixed properly.
ii. Cannot have physically distinct parts. ii. They have physically distinct parts.
iii. The constituents cannot be seen easily. iii. The constituents can be seen easily.
iv. The constituents cannot be easily seperated. iv. The constituents can be easily seperated.
Ex: sugar solution, air wateretc. sugar and sand mixture, milk, ink, paint, wood, blood etc.
9. What is a solution?
Ans. Homogenous mixture of two or more substances is called a solution.`
10. What are alloys?
Ans. Alloys are mixtures of two or more metals or metal and a non-metal and cannot be separated into their components by physical method.
11. Give an example of Alloy.
Ans. An example of an alloy is Brass. It is a mixture of 30% zinc and 70% copper.
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12. What are the two main components of a solution?
Ans. The two main components of a solution are -

(i) Solute and (ii) Solvent