Hello everyone we are beginning with a new chapter of your chemistry paper one that is solid state and in this particular module we are going to discuss definition of matter and its type and also we are going to cover characteristic of solids now whatever we see around us say from the point or television set to a point of an LCD player to that off of wooden door to that up in laptop or cold drink  or a steaming coffee to that of vehicle which is moving on the road or a plane which is moving in the air to that of the fume which is coming from the vehicle all of them fall into any simple term called as matter what i say that matter has three simple states of which the first one is solid the second one is liquid and a third one is gases if I talk about the example that a simple example of a solid as ice that liquid is water and out that of the gases steam and from the previous knowledge which we have we are aware that solids on heating convert to liquid, liquid on further heating converted to gas gases on cooling turns to liquid and liquids on further cooling turns two solids now let’s have a look at each of the example of each of the conversion in detail the first example shows you that conversion of solid into liquid that is precisely melting of ice this particular part will show you a water cycle where you will address that the water from the sea evaporates, evaporates to give you a cloud the cloud becomes dense and once again it comes in the form of rain and the here I see the first process is nothing but liquid to gas conversion and the second one is gas to liquid conversion  also if I talk about one more example the Near you will observe conversion of liquid into solid that’s one more exam full conversion of liquid into solid so you’re we saw the inter conversion of solid to liquid ,liquid to gas, gas to liquid and liquid to once again solid and if the question is – how does three states of matter inter convertible and the answer is simple that is intermolecular force of attraction and your eyes say that the physical state of matter is the result of interplay of intermolecular force of attractions like dipole-dipole interaction dipole induced dipole interaction London forces and hydrogen bonding and there are many more but this is the reason for the Inter conversion of three states of matter precisely if I talk about solids then in solids the intermolecular force IMF is the strongest in case of liquid the intermolecular force of attraction is moderate and in case of gases the inter molecular forces of attraction is weak we’re in case of solids if I talk about the mass shape density volume let’s talk about that in case of solids they have a definite shape they have a definite mass they have a definite volume and they have a definite  Density  where is a in case of liquids they have a definite mass they have a definite volume and density but they have an in definite shape we’re in case of gases they have in definite volume in definite density and in definite shape that’s a possible thing which you should know about this three states of matter out of the three states of matter that is solid liquid and gases liquids and gases already we have discussed in 11 standard chapter that the states of matter so right now you’re we are going to discuss solid state in detail so let’s start with the first part of the chapter that is characteristics of solids the first point say is that solids of fixed composition will have fixed mass volume shape and density solids or fixed composition will have fixed us volume shape and density the second characteristic solid is that the in case of solids the intermolecular distance is Dash(-) let’s try to answer this let’s have a look into this particular solid and if you look into the solid if you peep inside the solid will observe that the arrangement of particles let’s magnify that the arrangement of particle is very close and hence we say that the distance the distance the intermolecular distance in case of solids is very short the distance is the shortest now why the distance is the shortest is just because the Intermolecular our force of attraction is very strong and because the distance is very short and the intermolecular force of attraction is very strong we say that solids are hard they are rigid and they are in compressible let’s have a look at the last characteristics of solids the last characteristics or solids precisely talks about something called as the position and motion if you have a look at this particular arrangement and if I ask you what exactly is the position than the particles have a fixed position and if you have a look at the motion of the particles in the particles are in a vibratory motion they are in an oscillating motion so here I say the position is fixed and the motion vibratory and hence i conclude with my last characteristics of solid by saying that the Constituent particles and solids have fixed position and vibrantly motion that’s all we have for this particular module thank you so much.