Density can be defined in terms of the mass of a substance present in a certain volume.
i.e. Density = Mass/ volume
It helps classify and identify matter due to the following reasons:
1) Density is an intensive property. For a given substance the density will remain the same irrespective of the amount in which it is present.
For example: The density of Aluminum (Al) = 2.7 g/cm3. This value is a constant at a certain temperature and pressure. Therefore, the density will remain the same for 1 kilogram or 1 mg of Al
2) Different elements/compounds have different values of densities which is characteristic of that substance
Answer:
This is an example of a physical change because the ice cubes began to melt.
This is an example of a physical change because the ice cubes began to melt.
Explanation:
The above is the right answer to the question about the dissolution of the whole mixture mentioned in the excerpts above.
Double replacement i believe
Answer:
Bari oxit được tạo nên từ các nguyên tố Bari (Ba) và Oxi (O)
Explanation:
The atoms combine to form compounds to attain stability in nature. The combination of atoms takes place by sharing of electrons between the atoms or complete transfer of electrons from one atom to another. Generally, atoms combine to complete their octet, that is to possess eight electrons in their outer most shell (noble gas configurations) except hydrogen which can attain stability by two electrons in its outer most shell.
Since germanium has 4 electrons in its outer most shell so it needs 4 more electrons to complete its octet and attains the stability. Hydrogen has 1 electron in its outer most shell and it needs only 1 electron to attain stability so, each germanium will combine with 4 hydrogen atoms and thus forming 
molecule which is stable in nature.
Hence, is the formula of the hydride formed by germanium.
