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.
Choose one term from the following which includes the other three :
aerosol,
emulsion,
colloid,
sol
Q 3.
Name the property of any one of the components which can be used for separating the following mixture : Salt and Camphor
Q 4.
Name the property of one of the constituents which can be used to separate a mixture of salt and iodine
Q 5.
What are the properties of a colloid?
Q 6.
What are the physical states of dispersed phase and dispersion medium of a fog?
Q 7.
Classify the following as physical or chemical changes :
(i) Cooking of food
Q 8.
Name any two solid substances whose mixture can be separated by sublimation.
Q 9.
What are the physical states of dispersed phase and dispersion medium of a cloud?
Q 10.
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 11.
Which of the following is a sol ?
Shaving cream,
Milk,
Fog,
Soap solution,
Hairspray
Q 12.
What is meant by solute and solvent?
Q 13.
Describe sieving method.
Q 14.
Name a non-metal which is a good conductor of electricity.
Q 15.
Which of the following will show Tyndall effect ? Why ?
(a) Salt solution
(b) Starch solution
(c)Milk
Q 16.
(a) What is meant by a solution ? Give two examples of solutions.
(b)What is a suspension ? Give two examples of suspensions.
(c)
Q 17.
Name the source from which nitrogen and oxygen are obtained on a large scale.
Q 18.
On the basis of composition, how matter is classified?
Q 19.
What are aqueous solutions?
Q 20.
What is an unsaturated solution?
Q 21.
What are suspensions? Explain with an example.
Q 22.
What are the reasons for separating the constituents of a mixture?
Q 23.
Define Brownian movement in colloids.
Q 24.
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 25.
Identify the following as mixture or compound.
(i) blood
(ii) common salt
(iii) sugar
(iv) brass
Q 26.
What is an emulsion? Give examples
Q 27.
Give examples of liquids that are
(i) completely miscible
(ii) partially miscible
(iii) practically immiscible
Q 28.
How much water should be mixed with 12 mL of alcohol so as to obtain 12 % alcohol solution ?
Q 29.
A 5 per cent sugar solution means that:
(a)5 g of sugar is dissolved in 95 g of water.
(b)5 g of sugar is dissolved in 100 g of water.
Choose the correct answer.
Q 30.
What type of magnet is fitted on a crane to separate scrap iron objects from a heap of waste materials in factories ?
Q 31.
Name one pair of liquids which can be separated by using a separating funnel.
Q 32.
Which technique can be used to detect and identify traces of poison present in the stomach wash of a person ?
Q 33.
What is meant by Solubility?
Q 34.
What is saturated solution? Explain with an example.
Q 35.
What are the properties of suspensions?
Q 36.
What principle is applied in centrifugation? Give examples where this method is applied to separate mixtures.
Q 37.
A good method to separate alum (phitkari) from impure samples is
(a) Filtration
(b) Sedimentaion
(c) Crystallization
(d) Sublimation
Q 38.
Who used the term 'element' first time?
Q 39.
Name the property :
(a) which allows metals to be hammered into thin sheets.
(b)
Q 40.
(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 41.
State whether the following statements are true or false :
(a) Alcohol can be separated from a mixture of alcohol and water by a separating funnel.
(b) Salt and water can be recovered from an aqueous salt solution by the process of evaporation.
Q 42.
Name one pair of substances whose mixture can be separated completely by distillation.
Q 43.
Name the process which can be used to separate a mixture of salt solution and sand.
Q 44.
(a) Name the process by which common salt is obtained from sea-water.
(b) Name the process by which common salt is purified.
Q 45.
What are the characteristics exhibited by a pure substance?
Q 46.
List the points of differences between homogeneous and heterogeneous mixtures.
Q 47.
State the differences between compounds and mixtures.
Q 48.
Why do fish go in deep waters during day light?
Q 49.
Based on the type of solvent, how solutions are classified?
Q 50.
Based on the amount of solute in the given solution, how solutions are classified?
