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[A] : Soil particles , particularly clay...

[A] : Soil particles , particularly clay and organic matter in soil , contain negative charges that attract positively charged ions such as `Ca^(++) , K^(+)` and `Mg^(+ +)`
[R] : This attraction keeps these ions at a soil level where they are available to plants .

A

If both A and R are true and R is the correct explanation of A

B

If both A and R are true but R is not the correct explanation of A

C

If A is true and R is false

D

If both A and R are false

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Write the following steps is sequence that explain the phenomenon of redistribution of charges in an unchanged body in presence of a charged body . (A) As a result at one of the neutral body there is and excess of negatively charged particles and the other end there is an excess of positively charged particles. (B) Place a positively charged body near a neutral body. (C ) The negatively and positively chargeed particles in the neutral body get attracted and repelled by the positively charged body .

Read the passage given below and answer the following questions: Some colloids are stable by their nature, i.e., gels, alloys, and solid foams. Gelatin and jellies are two common examples of a gel. The solid and liquid phases in a gel are interdispersed with both phases being continuous. In most systems, the major factor influencing the stability is the charge on the colloidal particles. If a particular ion is preferentially adsorbed on the surface of the particles, the particles in suspension will repel each other, thereby preventing the formation of aggregates that are larger than colloidal dimensions. The ion can be either positive or negative depending on the particular colloidal system, i.e., air bubbles accumulate negative ions, sulphur particles have a net negative charge in a sulphur sol, and the particles in a metal hydroxide sol are positively charged. Accumulation of charge on a surface is not an unusual phenomenon-dust is attracted to furniture surfaces by electrostatic forces. When salts are added to lyophobic colloidal systems the colloidal particles begin to form larger aggregates and a sediment forms as they settle. This phenomenon is called flocculation, and the suspension can be referred to as flocculated, or colloidally unstable. If the salt is removed, the suspension can usually be restored to its original state, this process is called deflocculation or peptization. The original and restored colloidal systems are called deflocculated, peptized, or stable sols. Why does a small amount of salt have such a dramatic effect on the stability of a lyophobic colloidal system? The answer lies in an understanding of the attractive and repulsive forces that exist between colloidal particles. Van der Waals forces are responsible for the attractions, while the repulsive forces are due to the surface charge on the particles. In a stable colloid, the repulsive forces are of greater magnitude than the attractive forces. The magnitude of the electrical repulsion is diminished by addition of ionized salt, which allows the dispersed particles to aggregate and flocculate. River deltas provide an example of this behaviour. A delta is formed at the mouth of a river because the colloidal clay particles are flocculated when the freshwater mixes with the salt water of the ocean (source: Sarquis, J. (1980). Colloidal systems. Journal of Chemical Education, 57(8), 602. doi:10.1021/ed057p602 ) When Van der Waals forces are greater than forces due to the surface charge on the particles,

Read the passage given below and answer the following questions: Some colloids are stable by their nature, i.e., gels, alloys, and solid foams. Gelatin and jellies are two common examples of a gel. The solid and liquid phases in a gel are interdispersed with both phases being continuous. In most systems, the major factor influencing the stability is the charge on the colloidal particles. If a particular ion is preferentially adsorbed on the surface of the particles, the particles in suspension will repel each other, thereby preventing the formation of aggregates that are larger than colloidal dimensions. The ion can be either positive or negative depending on the particular colloidal system, i.e., air bubbles accumulate negative ions, sulphur particles have a net negative charge in a sulphur sol, and the particles in a metal hydroxide sol are positively charged. Accumulation of charge on a surface is not an unusual phenomenon-dust is attracted to furniture surfaces by electrostatic forces. When salts are added to lyophobic colloidal systems the colloidal particles begin to form larger aggregates and a sediment forms as they settle. This phenomenon is called flocculation, and the suspension can be referred to as flocculated, or colloidally unstable. If the salt is removed, the suspension can usually be restored to its original state, this process is called deflocculation or peptization. The original and restored colloidal systems are called deflocculated, peptized, or stable sols. Why does a small amount of salt have such a dramatic effect on the stability of a lyophobic colloidal system? The answer lies in an understanding of the attractive and repulsive forces that exist between colloidal particles. Van der Waals forces are responsible for the attractions, while the repulsive forces are due to the surface charge on the particles. In a stable colloid, the repulsive forces are of greater magnitude than the attractive forces. The magnitude of the electrical repulsion is diminished by addition of ionized salt, which allows the dispersed particles to aggregate and flocculate. River deltas provide an example of this behaviour. A delta is formed at the mouth of a river because the colloidal clay particles are flocculated when the freshwater mixes with the salt water of the ocean (source: Sarquis, J. (1980). Colloidal systems. Journal of Chemical Education, 57(8), 602. doi:10.1021/ed057p602 ) Settling down of colloidal particles to form a suspension is called:

Read the passage given below and answer the following questions: Some colloids are stable by their nature, i.e., gels, alloys, and solid foams. Gelatin and jellies are two common examples of a gel. The solid and liquid phases in a gel are interdispersed with both phases being continuous. In most systems, the major factor influencing the stability is the charge on the colloidal particles. If a particular ion is preferentially adsorbed on the surface of the particles, the particles in suspension will repel each other, thereby preventing the formation of aggregates that are larger than colloidal dimensions. The ion can be either positive or negative depending on the particular colloidal system, i.e., air bubbles accumulate negative ions, sulphur particles have a net negative charge in a sulphur sol, and the particles in a metal hydroxide sol are positively charged. Accumulation of charge on a surface is not an unusual phenomenon-dust is attracted to furniture surfaces by electrostatic forces. When salts are added to lyophobic colloidal systems the colloidal particles begin to form larger aggregates and a sediment forms as they settle. This phenomenon is called flocculation, and the suspension can be referred to as flocculated, or colloidally unstable. If the salt is removed, the suspension can usually be restored to its original state, this process is called deflocculation or peptization. The original and restored colloidal systems are called deflocculated, peptized, or stable sols. Why does a small amount of salt have such a dramatic effect on the stability of a lyophobic colloidal system? The answer lies in an understanding of the attractive and repulsive forces that exist between colloidal particles. Van der Waals forces are responsible for the attractions, while the repulsive forces are due to the surface charge on the particles. In a stable colloid, the repulsive forces are of greater magnitude than the attractive forces. The magnitude of the electrical repulsion is diminished by addition of ionized salt, which allows the dispersed particles to aggregate and flocculate. River deltas provide an example of this behaviour. A delta is formed at the mouth of a river because the colloidal clay particles are flocculated when the freshwater mixes with the salt water of the ocean (source: Sarquis, J. (1980). Colloidal systems. Journal of Chemical Education, 57(8), 602. doi:10.1021/ed057p602 ) Gelatin is a ________________ colloidal system.

Read the passage given below and answer the following questions: Some colloids are stable by their nature, i.e., gels, alloys, and solid foams. Gelatin and jellies are two common examples of a gel. The solid and liquid phases in a gel are interdispersed with both phases being continuous. In most systems, the major factor influencing the stability is the charge on the colloidal particles. If a particular ion is preferentially adsorbed on the surface of the particles, the particles in suspension will repel each other, thereby preventing the formation of aggregates that are larger than colloidal dimensions. The ion can be either positive or negative depending on the particular colloidal system, i.e., air bubbles accumulate negative ions, sulphur particles have a net negative charge in a sulphur sol, and the particles in a metal hydroxide sol are positively charged. Accumulation of charge on a surface is not an unusual phenomenon-dust is attracted to furniture surfaces by electrostatic forces. When salts are added to lyophobic colloidal systems the colloidal particles begin to form larger aggregates and a sediment forms as they settle. This phenomenon is called flocculation, and the suspension can be referred to as flocculated, or colloidally unstable. If the salt is removed, the suspension can usually be restored to its original state, this process is called deflocculation or peptization. The original and restored colloidal systems are called deflocculated, peptized, or stable sols. Why does a small amount of salt have such a dramatic effect on the stability of a lyophobic colloidal system? The answer lies in an understanding of the attractive and repulsive forces that exist between colloidal particles. Van der Waals forces are responsible for the attractions, while the repulsive forces are due to the surface charge on the particles. In a stable colloid, the repulsive forces are of greater magnitude than the attractive forces. The magnitude of the electrical repulsion is diminished by addition of ionized salt, which allows the dispersed particles to aggregate and flocculate. River deltas provide an example of this behaviour. A delta is formed at the mouth of a river because the colloidal clay particles are flocculated when the freshwater mixes with the salt water of the ocean (source: Sarquis, J. (1980). Colloidal systems. Journal of Chemical Education, 57(8), 602. doi:10.1021/ed057p602 ) Colloidal solutions are stable due to:

TRUEMAN BIOLOGY-Ecology -ASSERTION AND REASON
  1. [A] : An estimation of B.O.D gives an indication of the amount of poll...

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  2. [A] : PAN is a secondary pollutant . [R] : The secondary pollutants ...

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  3. [A] : Soil particles , particularly clay and organic matter in soil , ...

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  4. [A] : Algal blooms deplete dissolved O(2) levels in polluted water bod...

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  5. [A] : Orchids are most threatened plants in tropics . [R] : Tropical...

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  6. [A] : Vegetation in the catchment areas prevents flash floods in the d...

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  7. [A] : When the organisms live together in such a manner that one organ...

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  8. [A] : Aerenchyma is a specialized tissue in some water plants characte...

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  9. [A] : The pyramid of biomass indicates the decrease or the gradual red...

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  10. [A] : Climate is affected by vegetation . [R] : The indirect factors...

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  11. [A] : Man is the consumer of the ecosystem . [R] : An antiforest con...

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  12. [A] : The importance of ecosystem lies in flow of energy and cycling o...

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  13. [A] : Biomonitoring is reliable for determining the pollutants in air ...

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  14. [A] : The food webs are very important in maintaining the stability of...

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  15. [A] : If phytoplanktons are destroyed in the sea then it will effect t...

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  16. [A] : Epiphytes are not found in Delhi . [R] : Delhi has semi-arid c...

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  17. [A] : Water logged soils are physiologically dry . [R] : When the s...

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  18. [A] : There is a chemical warfare amongst some plants . [R] : The ro...

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  19. [A] : Total biomass on land is much more than that in water . [R] :...

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  20. [A] : Epiphytes differs from Lianas in that they are not rooted in th...

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