1. Matter :
It is anything that has a mass and a volume
2. Density :
It is the mass of volume unit of matter
3. Melting point :
It is the temperature at which the matter begins to
change from solid state to liquid state
4. Boiling point :
It is the temperature at which the matter begins to
change from liquid state to gaseous state
5. Melting :
It is the change of matter from solid state to liquid
state
6. Boiling :
It is the change of matter from liquid state to
gaseous state
7. Molecule :
It is the smallest part of matter which can exist
freely and it has properties of matter
8. Element :
It is the simplest pure form of matter which can be
analyzed chemically into simpler form
9. Compound :
It is a substance which is formed from combination
of atoms of different elements with constant weight
ratios
The density of milk =
1.03 gm/cm3
The density of water
= 1 gm/cm3
The melting point of
ice = 0 c
The boiling point of
water = 100 c
The mass of 1 cm3 of milk is 1.03 gm
The mass of 1 cm 3 of water = 1 gm
The ice begins to change into water at 0 c
The water begins to boil and change into water vapour
at 100 c
1. Color, taste and odour cannot be used to differentiate between water and
oxygen gas.
Because both of water and oxygen are colorless, tasteless and odourless
2. A piece of wood floats on water while a piece of lead sinks in it
Because the density of wood is less than the density of water while the
density of lead is more than the density of water
3. Ice floats on water surface although both are from one matter
Because the density of ice is less than the density of water
4. Water is not used to put out petrol fires
Because the density of petrol is less than the density of water so petrol floats
on water surface
5. Balloons filled with hydrogen and helium rise up n air?Because the density of
hydrogen and helium are less than the density of air
6. A piece of ice melts when it is left in air
Because the melting point of ice is low
7. Hardness can be used to distinguish between rubber and gold
Because the rubber is soft at room temperature while gold is not
8. Iron rods not copper rods are used to in building houses concrete
Because the hardness of iron is more than the hardness of copper
9. Electric wires are made of copper or aluminum and they are covered by a
plastic layer
Because copper and aluminum are good conductors of electricity but plastic s
a bad conductor of electricity
10.Screwdrivers are made of steel iron while their handles are made of wood
or plastic
Because steel iron is good conductor of electricity but wood and plastic are
bad conductor are bad conductor of electricity
11.Cooking pans are made of aluminum
Because the melting point of aluminum is high and it is good conductor of heat
12.Handles of cooking pans are made of wood or plastic
Because each of them is bad conductor of heat
13.Potassium and sodium are kept under kerosene surface
To prevent their reaction with oxygen in humid air
14.Steel bridges and the holders of light bulbs are painted from time to time
Metallic spare parts of cars are covered with grease
To protect them from rust and corrosion
15.Cooking pans made of aluminum are washed with a rough material
To remove any layer formed on them as a result of their reaction with the
oxygen of humid air
16.Silver and gold are used in making of jewels
Because they are chemically poor active
17.Active metals such as sodium lose their metallic luster when they are
exposed to moist air
Because they react easily with atmospheric oxygen
18.When you leave the per fume bottle open you smell it all over the room
Because the molecules of the perfume are in continuous motion and they
keep the properties of the perfume
19.A drop of ink (potassium permanganate) spreads through water
Because the molecules of ink or potassium permanganate are in continuous
motion
20.The volume of a mixture of water and alcohol is less than the sum of their
volume before mixing
Because some molecules of alcohol occupy the intermolecular spaces among
water molecule
21.It is very hard to fragmentize apiece of iron with your fingers while it is
easy to divide an amount of water into small droplets
Because intermolecular force among the iron molecules is very strong while
that is among water molecules is weak
22.Solid substances have definite shape and volume
Because the intermolecular spaces among its molecules are very narrow and
the intermolecular force is very strong
23.The liquid matter takes the shapes and volumes
Because the intermolecular spaces among its molecules are little big and the
intermolecular force among its molecules is weak
24.Gases have indefinite shapes and volumes
Because the intermolecular spaces among its molecules are large big and the
intermolecular force among its molecules is very weak
25.The matter changes from liquid state into gaseous state by heating
Because when a liquid substance is heated its molecules gain more energy and
its speed increases and at boiling point some of them overcome the inter
molecular force so they escape in the form of vapour
26.The matter changes from solid state into liquid state by heating
Because when a solid substance is heated its molecules gain more energy and
its speed increases and at melting point some of them overcome the inter
molecular force and become more freely so it changes into liquid state
27.Oxygen is an element while table salt is a compound
Because oxygen molecule is formed of two similar atoms while table salt
molecule is formed of two different atoms
Points of
comparison
Definition
Element
Compound
It is the simplest pure form of
matter which cannot be
analyzed chemically into
simpler form
It is a substance which is formed
from combination of atoms of two
or more different elements with
constant weight ratios
Atoms
Similar
Different
Examples
Hydrogen, Oxygen, aluminum
and sulphur
Water, carbon dioxide, sodium
chloride
Points of
The solid state
comparison
Motion of
limited
molecules
Intermolecular
Very small
spaces
(narrow)
Intermolecular
Very strong
forces
Volume
Definite
Shape
Definite
Examples
Iron - aluminum
The liquid state
The gaseous state
More free
Completely free
Intermediate
Very large
Intermediate
Very weak
Definite
Indefinite
Water – oil –
alcohol
Indefinite
Indefinite
Water vapour –
oxygen
1. Calculate the mass of a piece of sulphur its volume is
5 cm3 knowing that the density of sulphur is 2.1
gm/cm3
2. In an experiment for determining the density of
water the following results were recorded
Mass of empty baker = 65 gm
Mass of the beaker and water = 165 gm
The volume of water = 100 cm3
Calculate the density of water