Question:
What are the characteristics of mixture?
Answer:
1. Variable composition: The constituents of a mixture are present in any ratio. Example: A mixture of sand and salt can be in a ratio of 1:2 or 1:3 by weight.
2. Only Physical change: The mixture is a result of physical change. The constituents of a mixture do not bind each other by chemical bonds. Example: In air the main constituents, i.e., oxygen, nitrogen and carbon dioxide, do not bind each other with chemical bonds.
3. No specific properties: The properties of a mixture are the average of the properties of its constituents. Example: The properties of air are average common properties of nitrogen and oxygen.
4. Homogeneity: Most of the mixtures are heterogeneous, i.e., their constituents are not spread evenly throughout. However, some mixtures are homogeneous i.e. constituents are uniformly spread out. Example: In the mixture of iron and sulphur, at some places iron is more and at some places sulphur is more.
5. Separation Methods: In general, the constituents of mixture can be separated by applying suitable physical methods. E.g. Iron can be separated from the mixture of iron and sulphur with the help of a magnet.
6. Energy changes: In general, no energy is released or absorbed during the formation of a mixture. Example: On mixing iron and sulphur, heat energy is neither absorbed nor evolved.
Is Matter Around Us Pure?
Q 1.
What is the general name of the process by which tea-leaves are separated from prepared tea ?
Q 2.
Classify the following as physical or chemical changes :
(i) Cooking of food
Q 3.
Which of the following is a mixture ?Salt, Air, Water, Alum, Sugar
Q 4.
Name the process you would use to separate ammonium chloride from a mixture of sodium chloride and ammonium chloride.
Q 5.
Name one pair of liquids which can be separated by using a separating funnel.
Q 6.
Name the property of any one of the components which can be used for separating the following mixture : Salt and Camphor
Q 7.
Calculate the mass of glucouse and mass of water required to make 200g of 25% solution of glucouse.
Q 8.
How much water should be added to 15 grams of salt to obtain 15 per cent salt solution ?
Q 9.
What are non-aqueous solutions?
Q 10.
What is saturated solution? Explain with an example.
Q 11.
Define Brownian movement in colloids.
Q 12.
Name the property :
(a) which allows metals to be hammered into thin sheets.
(b)
Q 13.
What is the concentration of a solution which contains 16 g of urea in 120 g of solution ?
Q 14.
What is meant by saying that metals are malleable and ductile ?
Q 15.
What are pure substances ? Give two examples of pure substances.
Q 16.
Give two reasons for supposing that water is a compound and not a mixture.
Q 17.
What is meant by solute and solvent?
Q 18.
What is an emulsion? Give examples
Q 19.
Name a non-metal which is a good conductor of electricity.
Q 20.
Name the process which can be used to separate a mixture of salt solution and sand.
Q 21.
Name the apparatus you would use to separate oil from water.
Q 22.
What is an unsaturated solution?
Q 23.
What are the physical states of dispersed phase and dispersion medium of a fog?
Q 24.
Name the technique to separate
(i) butter from curd
(ii) salt from sea-water
(iii) camphor from salt
Q 25.
Name the property of one of the constituents which can be used to separate a mixture of salt and iodine
Q 26.
Name one pair of substances whose mixture can be separated by fractional distillation.
Q 27.
Name the source from which nitrogen and oxygen are obtained on a large scale.
Q 28.
State the differences between compounds and mixtures.
Q 29.
What is a solution? What are the properties of a solution?
Q 30.
What principle is applied in centrifugation? Give examples where this method is applied to separate mixtures.
Q 31.
Which of the following will show Tyndall effect ? Why ?
(a) Salt solution
(b) Starch solution
(c)Milk
Q 32.
What is supersaturated solution?
Q 33.
To make a saturated solution, 36 g of sodium chloride is dissolved in 100 g of water at 293K. Find its concentration at this temperature.
Q 34.
What are different ways to separate solid mixtures?
Q 35.
What are the reasons for separating the constituents of a mixture?
Q 36.
What is Chromatography?
Q 37.
Name the following :
(a) a lustrous liquid metal.
(b) a liquid non-metal
(c) a metal which can be cut with a knife
(d) a non-metal which is good conductor of electricity.
(e) an element which melts when kept on the palm.
(f) the best conductor of heat.
Q 38.
Give examples of liquids that are
(i) completely miscible
(ii) partially miscible
(iii) practically immiscible
Q 39.
(a) What is meant by (i) elements (ii) compounds, and (iii) mixtures ? Write down the names of two elements,two compounds and two mixtures.
(b) Classify the following into elements,
compounds and mixtures :
Marble,
Air,
Gold,
Brass,
Sand,
Diamond,
Graphite,
Petroleum,
Common salt,
Sea-water,
Chalk
Q 40.
Choose one term from the following which includes the other three :
aerosol,
emulsion,
colloid,
sol
Q 41.
(a) What is meant by a solution ? Give two examples of solutions.
(b)What is a suspension ? Give two examples of suspensions.
(c)
Q 42.
What type of magnet is fitted on a crane to separate scrap iron objects from a heap of waste materials in factories ?
Q 43.
Name any two solid substances whose mixture can be separated by sublimation.
Q 44.
What are the kinds of mixture?
Q 45.
What are aqueous solutions?
Q 46.
Why air is a mixture not a compound? Give reasons.
Q 47.
What are the advantages of preparing solutions?
Q 48.
Explain with an example what is a colloid?
Q 49.
What are the properties of a colloid?
Q 50.
What are the various methods to express concentration of a solution?
