Why is 人口 in this sentence 多, not 大? In English way of thinking (or my English way of thinking), a population is something that can be "huge" rather than "much"/ "many". Is Chinese way of thinking different? Is 人口 really as shape of the characters says - "mouths of people" rather than "population" in the English sense? People are many, but population is huge. Can I say "中国是世界上人口最大的国家"?
I've got one more question about this structure. Countries and cities can be big in two senses: in population or in territory. This sentence says "China is the biggest country in the world, in the sense of population". I guess I could change the category into the other one and say: 俄罗斯是世界上国土最大的国家. I put 大 here. Is it correct? Would 多 be correct?