vivek kumar gaurab roll no.:42

THIS IS MY HOMEWORK PAGE .

  Why do we observe that the level of water does not change even after dissolving salt in it??

ANS-  When we dissolve salt in water , the particles of salt get into spaces between particles of water so this shows that the level of water does not change.

properties of particle
particles force of attraction
particle are small
particle have kenetic energy
why sold are hard?
because their particle are closely packed and they have
more force of attraction

Q 2- Why diver is able to cut water?

ANS- Diver is able to cut water because the water is less denser and force of attraction is also less which results in the distance of molecules. The molecules are loosely packed.

Q 3- Why the smell of hot sizzling food reaches our nose?

ANS- Smell of hot sizzling food reaches our nose because the in hot temperature the molecules move faster which results in reaching the smell of food to our nose very quickly.

Ans 1-

 (a) 298 K

            (b) 646 K

Ans 2- 

 (a) 20*c

  (b) 197*c

Ans 3- 

(a) Naphthalene balls disappear with time as the temperature rises, it gets sublimated in gas without leaving any solid.

  (b) The molecules of perfume gets mixed with air molecules which is the least densest matter , that is why we gets smell of perfume sitting several meters away.

Ans 4-

 Oxygen -------> Water -------> Sugar 

Ans 5-

 (a) Liquid State

           (b) Solid State

    

 (c) Gaseous State

Ans 6-

 (a) (i) At room temperature the force of attraction between the molecules of water is medium that is why it is in liquid form.

                

 (ii) The room temperature (25*c) is higher than freezing point (0*c) which will make it solid and it is less than boiling point (100*c) which will make it gas.

            

(b) (i) At room temperature , the intermolecular force of solid is so high that its molecules gets packed together tightly.

                 

(ii) It has fixed shape and fixed volume.

Ans 7-

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

Ans 8-

 Steam will cause more serve burns.

fundamental unit of life

what is cell?
cellis the fundamental unit of life.

why does the water comes from cucumber when we add salt in it?
Ans The salt cause water to be drawn out of the cucumber. Water is drawn to it because it goes from a higher concentration to the lower concentration. When there is random motion that will always happen and is called diffusion. In the cells of cucumber allows the water through but not the salt.

EXERCISE
Make comparison between plant cell and animal cell?
plant cell
they have cell wall
they have large vocule in centre of the cell
they have plastid
ANIMAL CELL
THEY HAVE NOT CELL WALL
THEY HAVE SMALL FOOD VOCULE
THEY HAVE NO PLASTID

. How is prokaryotic cell different from a eukaryotic cell?