UnScramble this Word: r g s u a?

Questions

From an old name for which country did Horace Walpole coin the term Serendipity for happy finds made by chance?

What was the name of the research aircraft flown by Chuck Yeager when he broke the sound barrier in 1947?

In which art form was Donald Mcgill a specialist in the early 20th century?

Which term was coined by environmentalists in the 1990s for a strip of land sown with perrenial grasses to create an environment in which aphid eating insects can thrive?

In traditional Japanese dress what is an obi?