1. Ohio. Ohio is the only state, Sealand is a micronation, New Zealand is a country, and Pangea is a former continent.
2. India & China. US population is 326 million. France is only 67 million. India has 1.3 billion. China has 1.4 billion. Canada only has 36 million. Russia only has 144 million.
3. Sovreignity, land.
4. Not sure which it falls under, but the British government claims Sealand is not a country because it falls under British sovreignity, and also because it has no physical land.