What's the Kennection? #11

What rock, a kind of chert, was used to spark against steel in some of the earliest firearms?

In a famous 1940 speech, Winston Churchill pledged to the House of Commons his "blood, toil, tears," and what fourth offering?

What does the "U" stand for in the Cabinet department abbreviated HUD?

What 2009 sci-fi movie starred Sam Rockwell as a set of clones mining for helium on the title setting?

Mary Tyler Moore kept her own first name in her classic 1970s sitcom, but what was her character's last name?

What's the "Kennection"?