My querry is on baisc usage of relative pronoun, can anyone suggests, how both statements are grammatically incorrect
(i) This is one of the most interesting novels that
has appeared this year
(ii) This is the only one of his short stories that
are worth reading
The key here is the words "the only" in the second one. Those words make the subject singular.
Consider the following examples
Michel is one of my friends who have a car.
This means that among my friends who have a car -- Frank, Daniel, and so on -- Michel is one of them. The pronoun who refers to friends.
Michel is the only one of my friends who has a car.
Among my friends, only Michel has a car.