Every continent in the world is in a hemisphere. Everything on earth is in a hemisphere.
There is no such continent. (A small part of North America is in the eastern hemisphere.)
New Zealand is in the southern hemisphere. It is not actually part of any continent, but it is in the region (not continent) of New Zealand.
South America is the continent entirely in the Western Hemisphere and partly in the Northern Hemisphere. The equator crosses through the northern part of South America, placing some of the continent in the Northern Hemisphere.
Asia
South America
A state as a governmental division is the smallest, followed by country, which is part of a continent (usually one of 7), which is part of a hemisphere (any of 4 for the Earth).
Western Hemisphere
No, not every country is part of a continent. Some countries are considered transcontinental, meaning they span multiple continents or are located on islands that are not considered part of a specific continent. Examples include Russia, Turkey, and Indonesia.
Technically it is mostly in the eastern hemisphere, though it is generally regarded as part of the west.
North America is the continent primarily in the Western Hemisphere, and entirely in the Northern Hemisphere.Because Alaska is part of the US, and the state's islands (the Aleutians) extend across the International Date Line, that tiny part of North America is technically in the Eastern Hemisphere.
Arguably, all continents but Australia are a part of the Western Hemisphere. This means Europe, Africa, Asia, North America, and South America are a part of the Western Hemisphere; South America is the only continent fully in the Western Hemisphere. However, Australia is usually included with Oceania as a continent, and the region of Oceania is a part of the Western Hemisphere, so technically, all continents are a part of the Western Hemisphere.