Hades, god of the underworld
Poseidon.
Dan ae was not a Greek Goddess so therefore she has no symbol. She was a mortal, the mother of Perseus (whose father was Zeus).
The swastika was mainly a symbol in Hinduism. Athena is sometimes portrayed as wearing a robe covered in swastikas; however, it is not considered a symbol of Athena.
Athena is a Greek goddess whose symbols were the owl and olive tree. The Roman's identified her with their goddess, Minerva.
It was, Maximilien Robespierre.
Cornus is not a Greek god, but rather a genus of plants commonly known as dogwoods. In Greek mythology, the god of agriculture and fertility is Demeter, whose symbols include wheat, torches, and the poppy flower.
It is gold whose symbol is Au.
The power set of the empty has one member, which is the set whose member is the empty set . {phi} ( Actually the symbol for the empty set is the Norwegian letter O which resembles the Greek letter phi but is a different symbol )
Iron
You must mean, "Plutonium", whose symbol is 'Pu'.
The symbol for borilium is B, not to be mistaken with the element Boron, whose symbol is B as well. But there is no known element with the symbol "borilium".
Apollo