FRANK Solutions for Class 9 Chemistry Chapter 1 - Matter and its Composition: Law of Conservation of Mass
Chapter 1 - Matter and its Composition: Law of Conservation of Mass Exercise 8
Key: Matter occupies space and has mass.
(i) It should occupy space.
(ii) It should have mass.
Chapter 1 - Matter and its Composition: Law of Conservation of Mass Exercise 9
(a) Composition of Matter: Matter, whether in the solid, liquid or gaseous state, is composed of very small particles which may be molecules, atoms or ions.
(b) Arrangement of Particles: These particles have spaces lying between them and these spaces are referred to as intermolecular spaces or interparticle spaces.
(c) Forces of Attraction: The forces of attraction between the molecules of a given substance are called intermolecular forces. The magnitude of this force depends upon the state of the substance and on the magnitude of the intermolecular spaces. As the intermolecular space increases, the intermolecular force decreases.
(d) Motion of the constituent particles: The particles are always in a state of motion. In solids, they vibrate about their mean positions and in liquids and gases, they move randomly.
(e) The kinetic energy of the particles increases with rise in temperature. As the temperature is increased, the particles undergo motion more vigorously and more randomly.
(a) solid to liquid state
(b) gas to liquid
(c) liquid to gaseous state
(d) liquid to solid state
(b) Gas to liquid: The conversion of a substance from the gaseous state to its liquid state at a particular temperature is called condensation or liquefaction. On cooling, the gas molecules loose their kinetic energy in the form of lost heat and so molecular motion slows down. Decreased molecular motion causes a decrease in intermolecular space. The molecules come very close and the force of attraction between them correspondingly increases and the gas gets change into liquid.
(c) Liquid to gaseous state: The heat energy supplied to the liquid is absorbed by its molecules to gain kinetic energy and therefore the molecules move faster. This increases the intermolecular space. The intermolecular force of attraction decreases and liquid changes into gaseous state.
(d) Liquid to solid state: The conversion of a substance from the liquid state to solid state by cooling is called freezing. On cooling a liquid, the kinetic energy of the molecule is decreased. Due to decreased kinetic energy, the molecules cool down and come closer, thus reducing the intermolecular spaces. The force of attraction between the molecules thus increases. Now, the molecules are no longer in a position to be free or to migrate and liquid changes into a solid.
(b) Evaporation: The phenomenon involving the change of a substance from the liquid state to the gaseous state at room temperature or at any other temperature below its boiling point is called vaporisation or evaporation.
(c) Boiling point: The temperature at which a liquid boils and changes rapidly into a gas at atmospheric pressure is called boiling point of the liquid.
(d) Melting point: The temperature at which a solid substance changes into its liquid state at 1 atmospheric pressure is called the melting point of that substance.
(a) Size of naphthalene balls decreases
(b) Drying of wet clothes
(c) Wax melts in the sun
(d) Formation of clouds
(b) Drying of wet clothes - Evaporation
(c) Wax melts in the sun - Melting
(d) Formation of clouds - Evaporation and Condensation
The heat energy is absorbed by the liquid to convert it into vapour state. So, loss of heat causes cooling.
(a) Sublimation occurs only when the solid is heated
(b) An increase in pressure rises the melting point of a solid.
(c) Intermolecular spaces are maximum in solids.
(d) Gases do not have any free surfaces.
(a) That which occupy space and has mass.
(b) The state of matter that has definite mass,volume and shape.
(c) The state of matter that has no definite volume and shape.
(d) The state of matter that has the highest intermolecular attraction.
(e) The state of matter that has negligible intermolecular attraction.
(f) The state of matter that has very high compressibility.
(g) The state of matter that has only one surface
(h) The kind of matter that has fluidity.
(i)The change of state from solid to liquid.
(j) The change of state from liquid to gas.
(a) a solid (b) a liquid (c) a gas
(ii) Solids have definite mass, shape and volume.
Liquid:(i)The intermolecular forces of liquid molecules are intermediate of molecules of solids and gases while intermolecular spaces are greater than in solids.
(ii) Liquids have definite mass and volume but not definite shape. They take the shape of the container.
Gas: (i) The particles are held together by very weak intermolecular forces while intermolecular spaces are much greater than in solids.
(ii) Gases have definite mass but not definite shape and volume. They take the shape of the container.
(i) Wood has definite mass and shape.
(ii) Their intermolecular forces are very strong so they cannot flow.
Key: Intermolecular forces of attraction are the weakest in gases.
(a) Maximum movement of particles
(b) Maximum interparticle attractions
(c) Minimum spaces between particles
|1.State of packing||The particles are closely packed and their positions are also fixed.||The particles are loosely packed and their positions are not fixed.||The molecules are wide apart and their positions are also not fixed.|
|2.Energy associated||Particles can vibrate only to and fro about their mean positions. Therefore, they have small kinetic energy due to their motion.||The particles can move about more freely and have considerable kinetic energy due to their motion.||The particles move about freely and have maximum kinetic energy due to their motion.|
|3.Intermolecular forces||The particles are held together by strong intermolecular forces.||The particles are held together by weak intermolecular forces.||The particles are held together by very weak intermolecular forces.|
|4.Physical features||Solid has a crystalline structure with both definite size and definite shape.||Liquid does not have a definite shape but has definite volume and can flow from higher to lower level.||Gas has neither definite shape nor a definite volume but can flow and is easily compressible.|
(a) Solid, liquid and ______ are the three states of matter.
(b) In solid state of a substance, the force of attraction is very ______.
(c) The conversion of a solid directly into a gas is called ______.
(d) ______ is a process in which a vapour is changed into a liquid.
(e) In ______ state of a substance, the cohesive force is much weaker as compared to the separating force.
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