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Case study ( 4 Marks )

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Question 14 Marks
Read the following text carefully and answer the questions that follow:
Homogeneous mixtures are regarded as solutions or true solutions. Heterogeneous mixtures are of two types. These are suspensions and colloidal solutions. These differ in the size of the particles responsible for the difference in their properties. In a suspension, the particle size is more than $10^{-5} cm$ whereas in a colloidal solution, it ranges between $10^{-5} cm$ to $10^{-7} cm$. The two phases which constitute colloidal solutions, are dispersed phase and dispersion medium. Based upon their nature, the colloidal solutions are classified into eight types. The mixture of the nonreacting gases is always homogeneous irrespective of their nature. Therefore, it is not a colloidal solution.
i. Scattering of light occurs when a beam of light is passed through Blood. Why?
ii. What is Tyndall effect?
iii. What is called colloidal solution?
OR
Give an example of colloidal solution and identified their dispersed phase and dispersion medium?
Answer
i. Since blood is a colloid, so tyndall effect is observed when a beam of light is passed through it since the dispersed particles of a colloid are large, deflect light.
ii. The phenomenon by which the colloidal particles scatter light is called Tyndall effect. If light is passed through a colloid the light is scattered by the larger colloidal particles and the, beam becomes visible.
iii. Colloidal solutions area mixture in which the substances are regularly suspended in a fluid. A colloid is a very tiny and small material that is spread out uniformly all through another substance.
OR
Fog: Liquid (water drops) acts as dispersed phase and gas (air) as the dispersion medium.
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Question 24 Marks
Read the following text carefully and answer the questions that follow:
Culture fishery is rearing and harvesting of fish in small water bodies. The best method of culture fishery is composite fish culture, Here, fishes are selected on the basis of their growth rate, palatability, area of feeding and tolerance towards others. All of them have their exclusive zone and type of feeding. There are three zonessurface, middle zone and bottom. Each zone can have 2 or even 3 feeding options.You have studied the various fishes that can be accomodated in different zones of pond culture.
i. How many fishes can be accommodated at the bottom zone?
ii. What types of fish can occur on the surface zone of fresh water fish ponds?
iii. Where is fish Catla found in a fresh water culture pond?
OR
Which fish feeds on filamentous algae and decaying vegetation?
Answer
i. Three on detritus, vegetation and other organisms.
ii. Two, one herbivore and one carnivore
iii. Only in surface zone
OR
Rohu feeds on filamentous algae and decaying vegetation.
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Question 34 Marks
Answer
i. Adipose tissue.
ii. The cells of the connective tissue are loosely spaced and invaded in and intracellular matrix.
iii. Calcium and phosphorus compounds.
OR
Cartilage is found in the nose, ear, and trachea in the human body.
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Case study ( 4 Marks ) - Science STD 9 Questions - Vidyadip