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.
Name one pair of substances whose mixture can be separated by fractional distillation.
Q 4.
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 5.
Classify the following as physical or chemical changes :
(i) Cooking of food
Q 6.
What are non-aqueous solutions?
Q 7.
How much water should be mixed with 12 mL of alcohol so as to obtain 12 % alcohol solution ?
Q 8.
Which technique can be used to detect and identify traces of poison present in the stomach wash of a person ?
Q 9.
How many elements are there which are in gaseous state at room temperature?
Q 10.
State whether the following statement is true or false : Milk is a pure substance.
Q 11.
Who used the term 'element' first time?
Q 13.
What is saturated solution? Explain with an example.
Q 14.
Calculate the mass of glucouse and mass of water required to make 200g of 25% solution of glucouse.
Q 15.
Name a non-metal which is a good conductor of electricity.
Q 16.
Define a compound. Give two points of evidence to show that sodium chloride is a compound.
Q 17.
How much water should be added to 15 grams of salt to obtain 15 per cent salt solution ?
Q 18.
Name the property of any one of the components which can be used for separating the following mixture : Salt and Camphor
Q 19.
What type of magnet is fitted on a crane to separate scrap iron objects from a heap of waste materials in factories ?
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 a solution? What are the properties of a solution?
Q 23.
What are the advantages of preparing solutions?
Q 24.
What is an unsaturated solution?
Q 25.
What are the physical states of dispersed phase and dispersion medium of a fog?
Q 26.
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 27.
Name the elements are in liquid state at room temperature.
Q 28.
Why solutions do not exhibit Tyndall effect?
Q 29.
Which of the following is a mixture ?Salt, Air, Water, Alum, Sugar
Q 30.
What are pure substances ? Give two examples of pure substances.
Q 31.
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 32.
A 15% alcohol solution means :
(a)15 mL alcohol and 85 mL water.
(b)15 mL alcohol and 100 mL water.
Choose the correct answer.
Q 33.
Explain what happens when a beam of light is passed through a colloidal solution.
Q 34.
What is meant by the concentration of a solution ?
Q 35.
Name any two solid substances whose mixture can be separated by sublimation.
Q 36.
Name one pair of substances whose mixture can be separated completely by distillation.
Q 37.
How will you separate a mixture of chalk powder and water ?
Q 38.
Name the process which is used in milk dairies to separate cream from milk.
Q 39.
(a) Name the process by which common salt is obtained from sea-water.
(b) Name the process by which common salt is purified.
Q 40.
What are the kinds of mixture?
Q 41.
What do you mean by strength of the solution?
Q 42.
What are different ways to separate solid mixtures?
Q 43.
What is an emulsion? Give examples
Q 44.
Name a metal which is soft and a non-metal which is hard.
Q 45.
Name the property :
(a) which allows metals to be hammered into thin sheets.
(b)
Q 46.
What is meant by saying that metals are malleable and ductile ?
Q 47.
The properties of the product are different from those of the constituents. State whether this statement best describes an element, a compound or a mixture.
Q 48.
What name is given to those elements which are neither good conductors of electricity like copper nor insulators like sulphur ?
Q 49.
Fill in the following blanks with suitable words :
(a) An element is made up of only one kind of...........atoms
(b)Brine is a..........whereas alcohol is a.......
(c) Brass is an alloy which is considered a..........
(d) The three important metalloids are.............and...........
(e) The elements which are sonorous are called...............
Q 50.
Classify the following into elements and compounds :
(i)
