Misc: oklahoma city is the capital of ______?

Questions

1997 Great Events: Stock markets on this continent plunged in October.?

1997 Great Events: The Cassini space probe carried this dangerous substance.?

19th Cent Art: "Death of Marat" and "Oath of the Horatii", two of his better known works?

19th Cent Art: Color of ceiling in Van Gogh's "Night Cafe"?

19th Cent Art: French Impressionist who did "The Luncheon of the Boating Party", 1881?