Misc: What metal makes up most of earth's centre copper, gold or iron?

Questions

In 1914 German forces occupied---------- , Belgium, during World War I. ?

In 1918 Britain opened its offensive on the ---------- front during WW I. ?

In 1920 US's first commercial radio, 8MK (later WWJ), ---------- began daily broadcasting ?

In 1921 ---------- Susann, writer (Valley of the Dolls), born. ?

In 1921 Jacqueline---------- , writer (Valley of the Dolls), born. ?