Misc: In 1917 ---------- declares war on Germany and Austria at start of WW I. ?

Questions

Trivia : What type of clouds are also known as thunderheads?

Trivia : The depiction of the Mad Hatter in "Alice in Wonderland" reflected a poisoning of 19th century hatmakers from what?

Trivia : Whose laws first described the motion of the planets round the sun?

Trivia : What does the red spot on the Japanese flag represent?

Trivia : How many years old was the telephone before one was installed on the desk of the President of the United States?