CH 1 MATTER IN OUR SURROUNDING
Assignment 2
Answer the following questions:
1. A substance has a definite volume but no definite shape? State whether this substance is a solid, a liquid or a gas.
2. Arrange the following substances in increasing order of force of attraction between the particles. (a) Milk (b) Salt (c) Oxygen.
3. Why do gases exert more pressure on the walls of the container than solids?
4. Stone is solid. Give two characteristics of solid to prove this statement.
5. Why can a person move his hands through air and water but not through a table top?
6. Write 4 differences in the characteristics of solid, liquid and gas.
7. Why are gases compressible and not liquids or solid?
8. Can a rubber band be considered as solid as it can be stretched? Give reasons.
9. A gas completely fills a container in which it is kept. Give reasons as to why can a gas do so?
10. Write one question you would like to put forth for other classmates to answer in the next task.
Answers
Explanation:-
1. A substance has a definite volume but no definite shape? State whether this substance is a solid, a liquid or a gas.
Ans: Gases. A solid has definite volume and shape, a liquid has a definite volume but no definite shape, and a gas has neither a definite volume nor shape. The change from solid to liquid usually does not significantly change the volume of a substance.
2. Arrange the following substances in increasing order of force of attraction between the particles. (a) Milk (b) Salt (c) Oxygen.
Ans: The correct answer is oxygen, milk and salt. The first substance in the list is a gas therefore its molecules are bounded by loose forces of attraction.
In fact, you can find sufficient inter molecular space.
Milk is a liquid with forces of attractions between the molecules considerably higher than gas.
Salt is in powdered or solid form with maximum force of attraction.
3. Why do gases exert more pressure on the walls of the container than solids?
Ans: Gases exert more pressure on the walls of the container than solids do because there is more kinetic energy (thermal energy) in the gases which make its particle to move with great speed. So, they exert more pressure than solids.
5. Why can a person move his hands through air and water but not through a table top?
Ans: As in gas and liquid the particles are not closely packed so there is space between them but in solid particles are closely packed and there isn’t any free space.
6. Write 4 differences in the characteristics of solid, liquid and gas.
Ans: A solid has definite volume and shape, a liquid has a definite volume but no definite shape, and a gas has neither a definite volume nor shape. Technically speaking a fourth state of matter called plasma exists, but it does not naturally occur on earth, so we will omit it from our study here.
7. Why are gases compressible and not liquids or solid?
Ans: Gases are compressible because the intermolecular space is very large in gases, whereas liquids are not compressible because in liquids, the intermolecular space is less.
8. Can a rubber band be considered as solid as it can be stretched? Give reasons.
Ans: A rubber band can change its shape on stretching but it is a solid. This happens because pressure is applied on the band which makes it to change the shape and it gains its original shape when released. So, it’s a solid.
9. A gas completely fills a container in which it is kept. Give reasons as to why can a gas do so?
Ans: A gas completely fills the vessel in which it is kept because there is negligible force of attraction between the particles of gas. Thus, the gas particles move freely in all directions. b. A gas exerts pressure on the walls of the container because the particles of gas move randomly in all directions at high speed.