Wood & plastic are used in making handles of cooking pots.
VII. Rusting of metals:
When different metals are exposed to humid air for some time, some of them rust , others dont rust.
The ability of the metal to react with oxygen(rust) in the presence of water
Gold, silver platinum
Metallic parts of bridges, cars & light posts are painted periodically.
Painting prevents the reaction between the metal & oxygen & protects them against rust.
I. Complete the following statements:
1. The unit of mass is .while the unit of volume is .
2. Density is the .of a unit volume of a substance & its unit is .
3. Some examples of good electric conductors are .& .
4. .doesnt conduct heat or electricity.
II. Explain why:
1. A piece of lead sinks in a basin of water while a piece of wood floats on the surface.
2. A piece of ice which left at room temperature becomes water.
3. Metallic parts of bridges & light posts can stand for long time without rust.
III. Problems :
1. In the lab , the mass of a piece of iron was measured to be 87 g. When the piece was immersed in a graduated cylinder that contains 90 cm3 , water level increased up to 100 cm3. Calculate the density of iron.
2. The mass of an object is 8g. its density = 0.5 g/ cm3 . calculate the volume of the object.
IV. Whats meant by:
2. Melting point
3. Electric conductivity
V. Write the scientific term:
1. The temperature at which a substance changes from the liquid state to the gaseous state.
2. Substances which dont allow heat to pass through them.
open a bottle of perfume the smell of the perfume spreads in the room indicating that the perfume consists of tiny particles called molecules . they have the smell of the perfume & spread in the air.
With a dropper , put a drop of liquid colour in a beaker of water.
The colour spreads in the water
Ø Conclusion :
Molecules are in continuous motion.
Measure 50 ml of water with a graduated cylinder.
Measure 50 ml of vinegar then pour it in the cylinder that contains water..
The volume of water & vinegar is less than 100 ml.
Ø Conclusion :
Some vinegar molecules occupy the spaces between water molecules.
Matter consists of molecules. The spaces between the molecules are called intermolecular spaces .
Attraction forces keep molecules together .
Comparison between the 3 states of matter.
Points of comparison
Not Definite, they take the shape of their containers