11. Give reasons for the following:
a] Solids have a definite shape & are highly rigid, while gases have no definite shape & are least rigid.
b] Sugar can be distinguished from talcum powder using water.
c) Water on freezing turns into ice.
d] A bottle of perfume on opening evolves an odour which can be sensed over a long distance.
Answers
a) The intermolecular space between atoms of solid is very less, so they have a definite shape and are highly rigid . On the other hand, in gases, the intermolecular space is much more than that of solids, so they don't have definite shape and are less rigid.
b) Sugar can easily be dissolved in water without changing its appearance as it fits in the spaces between molecules of water whereas, talcum powder changes the appearance of water and moreover, it doesn't dissolve in water completely .So ,they are easily distinguished.
c)On freezing, the intermolecular space between molecules of water decreases so it gives it a definite shape and makes it somewhat rigid.
d)This is due to the diffusion property of gases. As, the intermolecular spaces between molecules of gases is so much that it overcomes the intermolecular attraction of molecules and so, they are easily diffused. And that's the reason why an odour can be sensed over a long distance after opening a bottle of perfume.
a) solids have definite shape and are highly rigid while gasses have no definite shape and are least rigid because in solids particles are tightly packed while in gasses particles are very loosely packed
b) talcum power can be distinguished from sugar by using water as sugar dissolves in water but talcum power doesn't dissolve
c) water on freezing turns into ice as it's particles also freeze due to drop in temperature
d) a bottle of perfume on opening evolves an odour which can be sensed over a long distance because when perfume was inside the bottle it was in form of liquid but after coming out it turned into gas
and in gas particles are very loosely packed