Ad
uestions
1. The mass per unit volume of a
substance is called density.
(density
mass/volume)
Arrange the following in order of
increasing density air, exhaust
from chimneys, honey, water,
chálk, cotton and iron.
2. (a) Tabulate the differences in
the characterisitcs of states
of matter.
(b) Comment upon the following:
rigidity, compressibility,
fluidity, filling a gas
container, shape, kinetic
energy and density.
3. Give reason
Answers
(1) Density
The increasing order of density is air < exhaust from chimney < cotton < water < honey < chalk < iron.
(2) (a) (i) Solids have a definite shape but lquids and gases have no definite shape.
(ii) Solids and liquids have definite volume but gases do not have definite volume.
(iii) Intermolecular forces of attraction are strongest in solids, slightly weaker in liquids and very weaker (almost negligible) in gases.
(iv) Solids are not compressible whereas liquids and gases are compressible.
(v) Solids cannot flow whereas liquids and gases can flow.
(b) Rigidity : It is the strongest force of attraction between particles and this property makes the solid rigid. Rigidity gives the perfect shape to solids, the particles in the solid are tightly packed. Solid does not get deformed easily by applying extra pressure.
Compressibility : Compressibility is mostly observed in gases. A lot of space between particles, a gas can be compressed to a higher extent. Solids have the least compressibility and liquids have little compressibility because of the least space between their particles.
Fluidity : The ability to flow is called fluidity. The less force of attraction and more space between particles makes the liquid and gas to flow easily. Fluidity is not observed in solids.
Filling of a gas container : Liquids do not fill a gas container completely, but gases fill the gas container completely in which it is stored. A gas can move in all the directions hence it fills the container completely.
Shape : Solids have a fixed shape. Liquid and gas occupy the shape of the container in which they are stored. This is due to the less force of attraction and more kinetic energy between the particles of liquids and the negligible force of attraction and highest kinetic energy between particles of gas.
Kinetic energy : The kinetic energy of particles of solid is the minimum. They only vibrate at their fixed position. The kinetic energy of particles of liquid is more as compared to solid. But they can slide above one another. The kinetic energy of particles in a gas is maximum.
Density : Density is defined as the mass per unit volume of a substance. The density of solid is highest, then comes liquid, and last comes the gases.
Air, water, exhaust from chimneys, chalk, cotton, honey, iron.