What is the smallest country in North America by land area?

What is the smallest country in Africa by land area? What is the smallest country in Asia by land area? What is the smallest country in Oceania by land area? Which of the following countries is an independent city-state with a land area of approximately 61 km²? What is the second-smallest country in the world by area? What is the smallest country in the European Union by area? Which of the following countries is NOT one of the five smallest countries in the world by land area? Which microstate is often described as the world's oldest surviving republic?