geography: Into what body of water does the Danube River flow?

Questions

In 1970, they became the first rock group to play NYC's Met. Opera House?

In 1973 Deep Purple released this popular double live album here in the U S?

In 1977, who recorded "Barracuda"?

In 1982 which group declared they were 'hungry like the wolf'?

In 1982, who recorded the lp called "The Number of the Beast"?