What is the most populous country in the Pacific Islands?

What is the most populous country in the European Union? What is the most populous country in the Commonwealth of Nations? Which country is the most populous in the Organization of American States? Which country is the most populous in the Baltic states? Which country is home to over 210 million people and is the 5th most populous country? Which country has a population of over 270 million people and is the 4th most populous country? Which of the following countries has a population of over 1 billion? Which of the following countries has a population density of over 1,000 people per square kilometer?