Question

1.Give reasons:

(a) A gas can fill the whole vessel in which it is enclosed.

(b) Solids cannot be compressed.

(c) Liquids can flow.


2.When sodium chloride is added to a definite volume of water and stirred well, a

solution is formed but there is no increase in the level of water. Why?

Answer 1

1... (A) because force of attraction between the particles of gas is very small ,its particles moves freely in all the possible direction.

(B). Because the particles don't move, solids have a definite shape and volume, and can't flow. Because the particles are already packed closely together, solids can't easily be compressed. Because there are lots of particles in a small volume, solids are dense.

(C). Liquids can flow easily because their particles can move over each other. When water is poured into a glass, the particles of water move over each other and into the corners of the glass. The particles keep on moving over each other as the water takes the shape of the glass.

2... Therefore, when NaCl is added to a definite volume of water and stirred well a solution is formed but there is no increase in the level of water due it's solubility nature and form aqueous form of sodium chloride.

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Answer 2

Answer:

1a: Gasses have very large inter-mollecular space and very low inter mollecular force of attraction. As a result the gasses diffuse out occupying the whole of the vessel (Practical: Spray perfume in one corner of your room and observe how even the other end scents)

1b: Solids have very low inter-mollecular space. They don't have enough space for contraction

1c: Same as (1a), the only difference being gasses diffuse due to their very low weight and liquids flow as the are heavier

2: Liquids have large inter-mollecular space. The NaCl added dissolves in water and its molecules fit themselves somewhere in the large inter-mollecular space which does not result in an increase in volume  

Explanation: