is this sentence correct?

It might be if we knew what kind of bloc ?

A group of nations, persons, .... or did you mean to use 'block'?


Joe(entirely something else) Nation

Sorry Joe, I don't know the source of the sentence.

I just don't know which of the following is correct or all of them:

This country is the most seriously affected by climate change.
This country is the most seriously affected one by climate change.
This country is most seriously affected by climate change.

Sentence one i think best describes what you want to say (because of the use of the definite article--the most seriously affected). Sentence two is rather awkward, and unlikely to be used to express the idea by a native speaker of English who writes well. Sentence three is a correct sentence but it only emphasizes the effect of climate change on that country, it offers no comparison to any other country.

All of them are awkward.

Best:
This country is the one most seriously affected by climate change.

No, they're not. Sentence one is not awkward at all. EFL students prefer to write their own sentences. They don't want you to write them for them.

True, but just the same, I like Punkey's suggestion. It sounds good.

The guy who loves to criticize others writing, with nary ever an explanation, gets a well deserved smackdown.