music: 70's Chart Toppers: Name The Artist: Rockin' Chair?

Questions

In which European art galleries are the 2 versions of Leonardo Da Vincis Virgin of the Rocks?

In a suit of armour which part of the body is protected by a greave?

Name given to a positive electrode?

Which classic 1939 Hollywood film derives from Maupassants Boule de Suif?

What is the name given to an outwork which defended the entrance of a castle or fortified town?