ADITI-Roll No.45(1)

CHAPTER 1 MATTER IN OUR SURROUNDINGS

                                                                   DATE 04.04.16

  QUESTION : Why do we observe that the level of water  does not change even after the                                  dissolving of salt in it ?
  ANSWER : We observe this because the particles of water  have gap between them  and the                      particles of  the salt  get into  the space and so the level does not increases .
          
                                                                    DATE 05.04.16
                                                     PROPERTIES OF   PARTICLES


                                   
               1  Particles are very small in size .
               2  Particles of matter  are continuously ,it means that they have kinetic energy .
               3  The particles of matter have space between them .

                                                               DATE 06.04.16 
   QUESTIONS : Why solids have fixed shapes ?
  ANSWER :  Solids have a fixed shapes because their the molecules in solid are in fixed                                  positions and are closed together so , they can  not move from one part to another                        part of the solid .

                                                                        DATE 07.04.16
          
              QUESTION : GIVE REASON

                   1     Why table is hard ?
  ANSWER  : Table is hard because the force of attraction in these molecules is very high and                      which results in close packing of molecules and it is very dense .
                
                  2     Why diver is able to cut water ?
 ANSWER : Diver is able to cut the water because it is less  denser and the attraction force is                  low so it has distance between the molecules and so the diver is able to cut the water .
                  3    Why the smell of hot sizzling food reaches our nose ?
 ANSWER : Smell of hot sizzling food reaches our nose because in the hot temperature
                      the molecules move faster which results in reaches our nose . 
                                                                                DATE 18.04,16
      
           EXERCISE

ANSWER 1
        1) 293 K     =   298 C

        2)470 K   =  646 C

ANSWER 2
           1) 25 C   = 20 C
        
           2) 373 K    = 197 C

ANSWER 3
               a) Naphthalene balls dissapear with time as the temperature rises , it gets sublimated                       in gas without leaving any solid .
              
               b) The molecules of perfumes gets mixed in the air molecules which is the least dense                              matter , that is why we get the smell perfume sitting several meters away .

ANSWER  4
      
               -   Oxygen - Water - Sugar

ANSWER 5

               a) Liquid State
                
               b) Solid State

                c)Gaseous State

ANSWER 6
                                  
               a) Water at room temperature has a medium force of attraction so it  is in liquid form .
                b) At room temperature , the inter molecular force  of  solid is so high that its                                            molecules get packed together tightly .
ANSWER 7

   At 273 k or 0 * c the ice will give more cooling than water bscause it can absorb more           heat than water due to its latend heat of fusion .

ANSWER 8
              Steam will cause more serve burns.

Latent heat of fusion

The heat required to change 1 kg of solid into liquid completely is known as latent heat of fusion. It is absorbed by a body during a constant temperature process that is specified in some way.

Latent heat of vaporization

 The heat required to change 1 kg of liquid into vaporous at atmospheric pressure is known as the latent heat of vaporization.

Evaporation

 The process of conversion of liquid into vapors is known as evaporation.

DATE 18.04.16

Factors affecting the rate of evaporation

1. Temperature- The rate of evaporation is directly proportional to the rise in temperature . more the temperature more will be the evaporation.

2. Humidity- The rate of evaporation is inversely proportional to the humidity. It means that the more the humidity is the less is the rate of evaporation.

3. Wind speed- The rate of evaporation is directly proportional to the wind speed. It means     that more is the wind speed more will be the rate of evaporation.

4. Surface area- The rate of evaporation increases when the surface area increases as when       the surface area will be increase the evaporation will also be increased.