Answer: Air
Explanation: Pure air is a mixture of several gases that are invisible and odorless. Consists of 78% nitrogen, 21% oxygen, and less than 1% of argon, carbon dioxide.
Answer:
The Only Viable Solution: A New Moon Shot
The electric light bulb didn't appear from efforts to develop better candles or telling people to use less light.
Answer:
When a chemical reaction occur, new substances are formed. The physical and chemical properties of new substances are different from initial substance.
Explanation:
Chemical change:
The changes, that occur due to change in the composition of a substance and result in a different compound is known as chemical change.
These changes are irreversible.
These changes occur due to chemical reactions.
These may not be observed with naked eye.
Examples:
Combustion of fuel or wood: that oil or wood convert into energy, CO2 and ash in case of wood .
Boiling of egg: that change the chemical composition of protein in the egg.
Physical change:
The changes that occur only due to change in shape or form but their chemical or internal composition remain unchanged.
These changes were reversible.
They have same chemical property.
These changes can be observed with naked eye.
Examples:
Water converting to Ice.
Water converting to gas.
In this water molecule remain the same only they rearrange themselves that change its state of mater not composition.
