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.
Name one pair of liquids which can be separated by using a separating funnel.
Q 3.
Classify the following as physical or chemical changes :
(i) Cooking of food
Q 4.
How much water should be added to 15 grams of salt to obtain 15 per cent salt solution ?
Q 5.
Name one pair of substances whose mixture can be separated by fractional distillation.
Q 6.
What type of magnet is fitted on a crane to separate scrap iron objects from a heap of waste materials in factories ?
Q 7.
What are non-aqueous solutions?
Q 8.
Name the property of any one of the components which can be used for separating the following mixture : Salt and Camphor
Q 9.
How much water should be mixed with 12 mL of alcohol so as to obtain 12 % alcohol solution ?
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.
Name the property :
(a) which allows metals to be hammered into thin sheets.
(b)
Q 12.
Give two reasons for supposing that water is a compound and not a mixture.
Q 13.
What is the concentration of a solution which contains 16 g of urea in 120 g of solution ?
Q 14.
Which technique can be used to detect and identify traces of poison present in the stomach wash of a person ?
Q 15.
Define Brownian movement in colloids.
Q 16.
Who used the term 'element' first time?
Q 17.
State whether the following statement is true or false : Milk is a pure substance.
Q 18.
Name a non-metal which is a good conductor of electricity.
Q 19.
Name the process you would use to separate ammonium chloride from a mixture of sodium chloride and ammonium chloride.
Q 20.
Name the process which can be used to separate a mixture of salt solution and sand.
Q 21.
What is saturated solution? Explain with an example.
Q 22.
Name any two solid substances whose mixture can be separated by sublimation.
Q 23.
What are the kinds of mixture?
Q 24.
Calculate the mass of glucouse and mass of water required to make 200g of 25% solution of glucouse.
Q 25.
Name the elements are in liquid state at room temperature.
Q 26.
Identify the following as mixture or compound.
(i) blood
(ii) common salt
(iii) sugar
(iv) brass
Q 27.
Which of the following is a mixture ?Salt, Air, Water, Alum, Sugar
Q 28.
Name the property of one of the constituents which can be used to separate a mixture of salt and iodine
Q 29.
Name the source from which nitrogen and oxygen are obtained on a large scale.
Q 30.
Name one pair of substances whose mixture can be separated completely by distillation.
Q 31.
What are different categories of pure substance?
Q 32.
Name two properties of a substance to check its purity?
Q 34.
List the points of differences between homogeneous and heterogeneous mixtures.
Q 35.
What is meant by solute and solvent?
Q 36.
What are the advantages of preparing solutions?
Q 37.
What is an unsaturated solution?
Q 38.
What are suspensions? Explain with an example.
Q 39.
What are different ways to separate solid mixtures?
Q 40.
How many elements are there which are in gaseous state at room temperature?
Q 41.
Name a metal which is soft and a non-metal which is hard.
Q 42.
What are pure substances ? Give two examples of pure substances.
Q 43.
Name a metal :
(a) which can be easily cut with a knife
(b) which forms amalgams
©which has not fixed shape
(d) which has a low melting point
(e) which is yellow in colour
Q 44.
Which of the two will scatter light: soap solution or sugar solution ? Why ?
Q 45.
What is the most common way of expressing the concentration of a solution ?
Q 46.
Choose one term from the following which includes the other three :
aerosol,
emulsion,
colloid,
sol
Q 47.
Define
(a) solute, and
(b) solvent
Q 48.
9.72 g of potassium chloride dissolves in 30 g of water at 70°C. Calculate the solubility of potassium chloride at that temperature.
Q 49.
(a) What is a physical change ? Give two examples of physical changes.
(b) What is a chemical change ? Give two examples of chemical changes.
Q 50.
(a) What is meant by a solution ? Give two examples of solutions.
(b)What is a suspension ? Give two examples of suspensions.
(c)
