music: Early Pop Rock: Oldest person to hit #1 on the singles chart.?

Questions

Which football team won the First Division Championship in the 1970s but is now in the lower divisions?

What instrument introduces Rhapsody in Blue?

In which science would you expect to come across the Witch of Agnesi?

Which famous painter was portrayed on screen by Kirk Douglas?

Which song and dance star of British musicals became Mrs Dale on radio?