No, it is false that Imperialism was the name given to the idea that Americans should expand across the nation to the Pacific Coast, since what you're referring to was known as "Manifest Destiny".
President Hoover was historically and categorically a bad president when it cam to treating the Depression in the United States because he was against government intervention.
Neutrality. (Assuming that's one of your options)
The United Nations has only four purposes stated in the UN Charter of 1945. These purposes focus mainly on the maintenance of world peace and security, on the harmonious relationship among nations, as well as on having cooperation in eliminating international problems and issues, and above all, be the center on achieving the first three purposes.
The Gothic element there is the horror that ensues after he hears the tapping. The character is alone during a spooky, dreary night, nobody found anywhere, and suddenly there is a mysterious tapping by someone, and it turns out that no-one tapped, which means either madness or ghosts, that are either way both elements of Gothic writing.