Answer:
Aluminum, boron, and gallium are likely together in one group because they have the same number of valence electrons, and carbon and germanium are likely together in another group because they have the same number of valence electrons.
Explanation:
1. compound
2. element
3. element
4. compound
5. compound
6. element
7. compound
8 element
1.4 g/cm3
Density = Mass/Volume
Mass = 21g
Volume = 15cm3
Density = 21/15 = 1.4
Answer: A
