Title: Iran.
Question: What Empire neighbored and had a rivalry with Safavid Iran?

Title: Gregorian calendar.
Question: What ruler decreed the change to the Gregorian calendar?

Title: Pitch (music).
Question: The just-noticeable difference, at which a change is perceived depends on what?

Title: Molotov%E2%80%93Ribbentrop Pact.
Question:
The pact according to Edward Carr’s view was to provide what between Germany and the Soviet Union?