Question:
(a) What is Tyndall effect? Doe true solution exhibit Tyndall effect.
(b) ‘‘Tyndall effect can be observed when sunlight passes through the canopy of dense forest. or we see a rich red sunset.’’ "Explain how this occurs.
Answer:
(a) The phenomenon by which colloidal particles scatter light is called Tyndall effect. The particles of a colloids scatter a beam of light passing through it and make its path visible. True solutions DO NOT show Tyndall effect. Scattering of light or Tyndall Effect is exhibited by Colloidal and Suspension particles.
(b) When sunlight passes through a canopy of forest, the colloidal misty air particles scatter the sunlight. Similarly, the seattering of light by smoke or dust particles (colloid) produce a rich red sunset.
Is Matter Around Us Pure?
Q 1.
Identify the following as mixture or compound.
(i) blood
(ii) common salt
(iii) sugar
(iv) brass
Q 2.
State the differences between compounds and mixtures.
Q 3.
What is a solution? What are the properties of a solution?
Q 4.
What are the characteristics exhibited by a pure substance?
Q 5.
What are the properties of suspensions?
Q 6.
What are the differences and similarities between concentration and solubility?
Q 7.
What are the reasons for separating the constituents of a mixture?
Q 8.
Name two properties of a substance to check its purity?
Q 9.
What factors affect the solubility of solvent and solute?
Q 10.
What are the physical states of dispersed phase and dispersion medium of a fog?
Q 11.
What are suspensions? Explain with an example.
Q 12.
What is meant by a pure substance?
Q 13.
How crystallization is better than evaporation?
Q 14.
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 15.
Why air is a mixture not a compound? Give reasons.
Q 16.
What are the advantages of preparing solutions?
Q 17.
Name the elements are in liquid state at room temperature.
Q 19.
Based on the type of solvent, how solutions are classified?
Q 20.
Based on the amount of solute in the given solution, how solutions are classified?
Q 21.
What are the properties of a colloid?
Q 22.
How many elements are there which are in gaseous state at room temperature?
Q 23.
List the points of differences between homogeneous and heterogeneous mixtures.
Q 24.
A good method to separate alum (phitkari) from impure samples is
(a) Filtration
(b) Sedimentaion
(c) Crystallization
(d) Sublimation
Q 25.
How much water should be mixed with 12 mL of alcohol so as to obtain 12 % alcohol solution ?
Q 26.
What are the physical states of dispersed phase and dispersion medium of a cloud?
Q 27.
State three reasons why you think air is a mixture and water is a compound.
Q 28.
How will you separate iron pins from sand ?
Q 29.
Name the process you would use to separate a mixture of two miscible liquids (like acetone and water).
Q 30.
What are the various methods to express concentration of a solution?
Q 31.
Name the technique to separate
(i) butter from curd
(ii) salt from sea-water
(iii) camphor from salt
Q 32.
Choose one term from the following which includes the other three :
aerosol,
emulsion,
colloid,
sol
Q 33.
What is difference between colloids and suspensions ?
Q 34.
21.5 g of sodium chloride dissolves in 60 g of water at 25°C. Calculate the solut water at that temperature.
Q 35.
(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 36.
What is meant by Solubility?
Q 37.
What is Chromatography?
Q 38.
Which of the following is a mixture ?Salt, Air, Water, Alum, Sugar
Q 39.
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 40.
(a) What is meant by a solution ? Give two examples of solutions.
(b)What is a suspension ? Give two examples of suspensions.
(c)
Q 41.
Which technique can be used to detect and identify traces of poison present in the stomach wash of a person ?
Q 42.
Calculate the mass of glucouse and mass of water required to make 200g of 25% solution of glucouse.
Q 43.
Is air a mixture or a compound ? Give three reasons for your answer.
Q 44.
Name the process you would use to separate a mixture of water and alcohol.
Q 45.
What are different categories of pure substance?
Q 46.
What is a compound? Give an example.
Q 47.
Why do fish go in deep waters during day light?
Q 48.
What are non-aqueous solutions?
Q 49.
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 50.
Why solutions do not exhibit Tyndall effect?
