* Common noun: When "china" refers to the country of China, it's a common noun. Common nouns are general names for people, places, or things (e.g., dog, city, book).
* Concrete noun: When "china" refers to ceramic tableware or porcelain, it's a concrete noun. Concrete nouns are things that can be seen, touched, or experienced with the senses.
Abstract nouns refer to concepts, ideas, qualities, or states of being (e.g., happiness, freedom, love). "China" doesn't fit this definition, so it's not an abstract noun.