Describe the similarities of compound and elements

Compounds like
C
O
2
are made of atoms put together to make stable molecules.
Elements like
O
2
are made of atoms put together to make stable molecules.
All Compounds are always made of atoms of different types to make molecules.
Elements when they are molecules are always made of atoms of the same type.
Many elements especially metals and Noble gases are not found as molecules, but as atoms only.
Metals often form metallic bonding where a sea of electrons holds numbers atoms together but not as molecules.
Noble gases ( group VIII A) rarely form molecules but are found as individual atoms.

The answer is c. 320 g

Mg-26 and mg-24 are pair of isotopes. isotopes are defined as atoms of the same element having same atomic number but different mass number. i hope that was .