B. Give reasons for the following statements.
1. Solids have a fixed shape and size.
2. Solids expand very little on heating.
3. The fragrance of incense stick spreads out in air to a distan
4. Molecules of gases move freely in all the directions.
5. Liquids expand more than solids.
C.
Answer in short.
1. How is an atom different from a molecule?
2. Explain diffusion with the help of an example,
3. Do gases have a fixed shape and size? Give reason.
4. Why can the molecules in a liquid move freely?
AT LENGTH
Answers
Answer:
1. Solids have a fixed shape and a fixed size. The particles are very close together and held in place by strong forces (bonds). Their particles cannot move around, but they do vibrate. Because the particles cannot move around, a solid has a fixed shape.
2. When a solid is heated, its atoms vibrate faster about their fixed points. The reljati1ve increase in the size of solids when hhkeatied is therefore small. ... Liquids expand for the same reason, but because the bonds between separate molecules are usually less tight they expand more than solids.
3. Diffusion is a phenomenon which occurs in gaseous molecules. ... in case of incense stick, the fragrance is actually a gas, the molecules of it undergo diffusion and spread everywhere and thus we are able to sense(smell) the fragrance at a distance also.
4. The molecules of a gas are free to move randomly in all directions. During their motion, they collide with one another and also with the walls of the container. The constant bombardment of the molecules on the walls of the container exerts a steady force.
5. All three states of matter (solid, liquid and gas) expand when heated. The atoms themselves do not expand, but the volume they take up does. ... Liquids expand for the same reason, but because the bonds between separate molecules are usually less tight they expand more than solids.
Answer in short
1. Atoms are single neutral particles. Molecules are neutral particles made of two or more atoms bonded together.
2. Diffusion is a physical process that refers to the net movement of molecules from a region of high concentration to one of lower concentration. The material that diffuses could be a solid, liquid or gas. An example of this is the way the noxious smell of ammonia gas spreads in air. ...
3. Gases have neither fixed shape nor fixed volume. This is because of the weak intermolecular foces of attraction in the gases. They take the shape and volume of the container in which they are placed.
4. .molecules in liquid can move about a little. They are less tightly packed then in solids i.e. they have bigger intermolecular space. The molecules of liquid do not have fixed position. The intermolecular force of attraction between the molecules of a liquid is weaker than those in solids.
Answer:
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