1. Give reason for the following observation:
A gas completely fills the container in which it is kept
A gas exert pressure on the wall of the container
A wooden table is called a solid.
We can easily move our hand through liquid but we can not do so
in case of solid
2. Arrange the following in the order of increasing density
Air, exhaust from chimney, honey, iron, cotton , water, chalk
3. Liquid generally have lower density as compared to solid but contrary to
that ice (which is solid) floats on water
4. Why the following substances are considered as solid even though they
do not fulfill the following mentioned properties of solids:
Rubber band which changes its shape on stretching
Sponge which can be compressed
Sugar crystals which When poured in a container take the shape
of container .
Answers
Answer:
Explanation:
1.
i) Gases have a negligible intermolecular force of attraction between the particles of gas. The random motion of particles in all the directions is experience in the vessel. Hence, the gas fills completely the vessel in which it is kept.
ii) The pressure exerted by a gas is due to the random motion of particles in the gas. Gases have weak intermolecular forces and the particles in continuous random motion and these particles collide with the walls of the container. These collisions with the walls of the container exerts pressure on the gas.
iii)A wooden table should be called a solid. Reason: It has a definite shape and volume. It is very rigid and cannot be compressed i.e., it has the characteristics of a solid. There is a strong force of attraction between molecules of wood and intermolecular space is the least.
iv) In air, there is lot of empty space between the molecules and the forces between the particles are almost negligible. Hence, we can move our hand in air. However we cannot move our hand in a solid block because there are strong forces of attractions between particles in a solid and there is no empty space between them.
2. The increasing order of density is air < exhaust from chimney < cotton < water < honey < chalk < iron.
3.Water does exist in the form of ice or snow in the solid-state. ... Liquids generally have lower density as compared to solids but ice floats on water. When water freezes to form ice, some empty spaces are created. As a result, volume increases for the same mass of water.
4 i) A rubber band is considered a solid because it changes shape under the action of force and when the force is removed, it regains its original shape
ii) on pressing the air is expelled. The sponge is matter and considered as solid because it has a definite volume and shape does not change unless compressed. A sponge can be compressed easily even though it can be considered as solids because they have minute pores in it which are filled with air.
iii)even though , common salt and sugar crystals when poured in any container, they take the shape of container, still each granule of common salt and sugar retain their fixed shape and volume . Hence they are considered as Solids
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